^ ^ 


Qs:^s^s:^=^=^s;^r^s‘g^aj^:^s$^s05£^z:$^sj^s;j^r^Q 


^earniitg  aub  ^fabor. 


LIBRARY 


University  of  Illinois. 

CLASS.  BOOK.  VOLUME. 

..'S'sl. N\."^io.  'c \ 

Accession  No. 


MARYLAND  GEOLOGICAL  SURVEY 


EOCENE 


MARYLAND 


GEOLOGICAL  SURVEY 

LIBRARY 

• OF  the 

UNIVERSITY  of  ILLlNUiS 


EOCENE 


BALTIMORE 

THE  JOHNS  HOPKINS  PRESS 
1901 


J'rt^bentvafi)  Company 

BALTIMORE,  MD.,  U.  S.  A. 


> 

0 

r 

>) 


COMMISSION 

JOHN  WALTEE  SMITH, President. 


JOSHUA  W.  HERING, 


DANIEL  C.  GILMAN, Executive  Officer. 


PRESIDE^fT  OF  THE  JOHNS  HOPKINS  UNIVERSITY. 


R.  AY.  SILVESTER, Secretary. 


PRESIDENT  OF  THE  MARY'LAND  AGRICULTURAL  COLLEGE. 


\ 


GOVERNOR  OF  MARYLAND. 


COMPTROLLER  OF  MARYLAND. 


Digitized  by  the  Internet  Archive 
in  2016 


/ 


https://archive.org/details/eoceneeocenedepo1190claf 

♦ 

i 


SCIENTIFIC  STAFF 


W^r.  Bullock  Clakk, State  Geologist. 

SUPEKIXTEXDEXT  OF  THE  SURYEAT. 


Edward  B.  Mathey’s,  . . . Assistaxt  State  Geologist. 

CHIEF  OF  THE  PIEDMONT  DISTRICT. 


Charles  S.  Prosser, 

CHIEF  OF  THE  APPALACHIAN  DISTRICT. 


George  B.  Shattuck, 

CHIEF  OF  THE  COASTAL  PLAIN  DISTRICT. 


Harra'  Fieldixg  Eeid, 

CHIEF  OF  THE  HIGHWAY  DIVISION. 


L.  A.  Bauer, 

CHIEF  OF  THE  DIVISION  OF  TERRESTRIAL  MAGNETISM. 

And  Y'ith  the  cooperation  of  several  members  of  the  scientific  bureaus 
of  the  Xational  Government. 


LETTER  OF  TRANSMITTAL 


To  His  Excellency  John  Walter  Smith, 

Governor  of  Maryland  and  President  of  the  Geological  Survey  Com- 
mission. 

Sir: — I have  the  honor  to  present  herewith  the  first  volume  of  a 
series  of  reports  dealing  with  the  systematic  geology  and  paleontology 
of  Maryland.  A clear  comprehension  of  oiir  geological  formations  is 
based  on  a knowledge  not  only  of  the  materials  out  of  which  the  strata 
are  composed,  hut  also  of  the  remains  of  animal  and  plant  life  which 
are  entombed  in  the  rocks  themselves.  A thorough  knowledge  of  both 
these  factors  is  essential  as  a basis  for  a complete  interpretation  of  the 
mineral  resources  of  the  state,  while  the  educational  and  scientific 
value  of  such  information  cannot  be  overestimated.  It  is  the  purpose 
of  the  Survey  to  publish  a number  of  similar  reports  which  will  embrace 
the  entire  sequence  of  Maryland  formations.  Already  much  progress 
has  been  made  in  the  investigations  for  the  subsequent  volumes  of  the 
series.  I am. 

Very  respectfully, 

William  Bullock  Clark, 

State  Geologist. 

Johns  Hopkins  University, 

Baltimore,  Aprils  1901. 


CONTENTS 

PAGE 

PREFACE 15 

THE  EOCENE  DEPOSITS  OF  MARYLAND.  By  William  Bullock  Clark 

AND  George  Curtis  Martin 19 

Introduction 21 

Historical  Review 24 

Bibliography 31 

General  Stratigraphic  Relations 44 

Cretaceous  45 

Eocene 46 

Neocene 47 

Pleistocene 48 

Distribution  of  Strata  49 

Delaware 49 

Maryland 50 

Virginia 51 

General  Character  of  the  Deposits 52 

Composition 52 

Strike  and  Dip 53 

Thickness 54 

Origin  of  the  Materials . 54 

Origin  of  Greensand 55 

Depth  of  Sedimentation 57 

Stratigraphical  and  Paleontological  Characteristics 57 

Formations  and  Faunal  Stages 58 

The  Aquia  Formation  or  Stage 59 

The  Piscataway  Member  or  Substage 60 

The  Paspotansa  Member  or  Substage 62 

The  Nanjemoy  Formation  or  Stage 64 

The  Potapaco  Member  or  Substage 65 

The  Woodstock  Member  or  Substage 66 

Local  Sections 67 

The  Potomac  River  Section 67 

Other  Sections 71 

Geological  and  Geographical  Distribution  of  Species 73 

Table  showing  Distribution  of  Maryland  Eocene  species 73 

Correlation  of  Deposits 82 

Correlation  of  the  Deposits  within  the  Middle  Atlantic  Slope 82 

Correlation  of  the  Deposits  with  the  Eocene  Formations  of  the  Gulf  States.  83 

Paleontological  Criteria 84 

Geological  Criteria 89 

European  Equivalents 91 


12 


CONTENTS 


PAGE 

SYSTEMATIC  PALEONTOLOGY,  EOCENE 93 

Reptilia.  By  E.  C.  Case 95 

Pisces.  By  Charles  R.  Eastman 98 

Arthropoda.  By  E.  O.  Ulrich 116 

Mollusca.  By  W.  B.  Clark  and  G.  C.  Martin 122 

Mollnscoidea 203 

Brachiopoda.  By  W.  B.  Clark  and  G.  C.  Martin 203 

Bryozoa.  By  E.  O.  Ulrich 205 

Coelenterata.  By  T.  Wayland  Vaughan 222 

Echinodermata.  By  W.  B.  Clark  and  G.  C.  Martin 232 

Protozoa.  By  R.  M.  Bagg,  Jr 233 

Plantae.  By  Arthur  Hollick 258 

Explanation  of  Plates 261 

Genekal  Index 317 

Paleontological  Index 323 


ILLUSTRATIONS 

PLATE  FACING  PAGE 

I.  Map  showing-  Distribution  of  Eocene  Deposits  in  Maryland 21 

II.  Views  of  Surface  of  Eocene  Country 44 

Fig.  1. — Farm-  and  wood-lands  along  South  Riyer 44 

“ 2. — Farm-lands  near  Annaiiolis  Waterworks 44 

III.  Views  of  Eocene  Sections 48 

Fig.  1. — Zones  2 to  6 at  mouth  of  Aquia  Creek 48 

“ 2. — Blocks  of  Zone  9,  largely  composed  of  TnrriteUa 
mortoni 48 

IV.  Views  of  Eocene  Sections 56 

Fig.  1. — Fort  Washington  bluti',  basal  Eocene  overlying 

Cretaceous 56 

Fig.  2. — Zones  2 to  4 at  base  of  Aquia  Creek  blutf 56 

V.  General  Columnar  Section  of  Eocene  Deposits  in  Maryland 64 

VI.  Local  Columnar  Sections  of  Eocene  Deposits  in  the  Potomac 

Valley 68 

VII.  Views  of  Eocene  Sections 72 

Fig.  1. — Lower  Eocene  Deposits  on  Severn  River 72 

“ 2. — Indurated  layer  of  Upper  Marlboro,  overlying  Bryo- 

zoan  Sand 72 

VIII.  Views  of  Eocene  Sections 84 

Fig.  1. — Contact  of  Nanjemoy  and  Aquia  Formations  in  Valley- 

of  Beard  Creek,  Anne  Arundel  County 84 

Fig.  2. — Contact  of  Nanjemoy  and  Aquia  Formations  at  Upper 

Marlboro 84 

IX.  Views  of  Eocene  Sections 88 

Fig.  1. — Railroad  Cut  near  Upper  Marlboro  showing  Nanjemoy 

Formation  overlain  by  later  deposits 88 

Fig.  2. — Popes  Creek  bluff  showing  Zone  17  overlain  by 

Miocene  Diatomaceous  earth 88 

X,  XI.  Reptilia 262-263 

XII-XV.  Pisces 264-267 

XVI.  Arthropoda — Crustacea 268 

XVII-XIX.  Mollusca — Cephalopoda  269-271 

XX-XXVIII.  Mollusca — Gastropoda 272-280 

XXIX.  Mollusca — Gastropoda  and  Scaphapoda 281 

XXX-LVII.  Mollusca— Pelecypoda 282-309 

LVIII.  Molluscoidea — Brachiopoda 310 

LIX,  LX.  Molluscoidea — Bryozoa 311-312 

LXI.  Echinodermata  and  Coeleuterata 313 

LXII,  LXIII.  Protozoa — Foraminifera  314-315 

LXIV.  Protozoa — Foraminifera,  and  Plantae 316 


PREFACE 


The  present  volume  is  the  first  of  a series  of  reports  dealing  with 
the  systematic  geology  of  Maryland.  These  reports  will  appear  from 
time  to  time  as  the  several  investigations  are  completed,  but  not  neces- 
sarily in  geological  sequence.  By  reference  to  Volume  I of  the  Survey 
it  will  be  seen  that  the  geological  sequence  of  Maryland  rocks  is  as 
follows: 

{Pleistocene 
Neocene 
Eocene 


Mesozoic 


Cretaceous 

Jurassic-Triassic 


r 

Paleozoic 


Permian-Carboniferous 

Devonian 

Silurian 

Cambrian 


Archean  Algonkian-Archean 


Some  of  these  divisions  are  more  extensively  developed  in  Maryland 
than  others  so  that  the  contemplated  reports  will  differ  greatly  in  size. 
The  oldest  division,  comprising  the  Algonkian-Archean,  is  entirely  des- 
titute of  organic  remains  in  Maryland,  while  the  Jurassic-Triassic  is 
nearly  so.  The  other  seven  divisions,  however,  contain  either  rich 
faunas  or  floras;  three  of  them,  the  Permian-Carhoniferous,  the  Cre- 
, taceous  and  the  Pleistocene  containing  both  animal  and  plant  fossils. 

These  reports  when  completed  will  give  both  to  the  geologist  and  to 
the  general  reader  a comprehensive  view  of  the  past  history  of  Maryland 
territory  from  the  earliest  geological  period  to  the  present  day.  For 
educational  purposes  the  volumes  cannot  fail  to  have  much  value,  and 
will  find  frequent  use  in  the  hands  of  those  who  are  seeking  to  acquire 
a knowledge  of  the  ph}^sical  and  faunal  history  of  the  State  of  Maryland. 

The  present  volume  on  the  Eocene  deals  with  the  earliest  period  of 
the  Cenozoic  and,  with  the  Neocene,  embraces  what  is  frequently  de- 


16 


PKEFACE 


nominated  by  geologists  as  the  Tertiary.  As  will  be  shown  in  later 
pages  the  Tertiary  rocks  of  Maryland  are  of  wide  extent  and  contain 
much  of  interest  from  both  a scientific  and  practical  standpoint. 

The  Eocene  deposits  of  Maryland  have  received  for  many  years  the 
close  attention  of  .the  senior  author  of  this  paper,  and  his  observations 
have  been  supplemented  recently  by  the  work  of  the  junior  author.  A 
report  made  by  the  senior  author  to  the  Director  of  the  U.  S.  Geo- 
logical Survey  in  1896  is  extensively  drawn  upon  for  the  present  vol- 
ume, many  of  the  general  descriptions  being  taken  directly  therefrom, 
with  such  changes  and  additions  as  the  present  enlarged  knowledge  of 
the  subject  may  require. 

Dr.  K.  M.  Bagg,  Jr.,  also  spent  portions  of  two  field  seasons  in  a 
study  of  the  local  stratigraphy  under  the  personal  direction  of  the  State 
Geologist  and  prepared  a series  of  preliminary  maps  covering  a large 
part  of  the  area. 

The  paleontological  investigations  have  been  jointly  conducted  by 
several  experts.  In  addition  to  the  sections  for  which  the  authors  of 
the  report  are  personally  responsible,  aid  has  been  rendered  in  others 
by  several  well-known  students. 

The  Eeptilia  have  been  studied  by  Dr.  E.  C.  Case  of  Milwaukee,  Wis- 
consin; the  Eishes  by  Dr.  Charles  R.  Eastman  of  Harvard  University, 
Cambridge,  Massachusetts;  the  Crustacea  and  Bryozoa  by  Mr.  E.  0. 
Ulrich  of  Newport,  Kentucky;  the  Corals  by  Mr.  T.  Wayland  Vaughan 
of  the  U.  S.  Geological  Survey;  the  Protozoa  by  Dr.  R.  M.  Bagg,  Jr., 
of  Colorado  Springs,  Colorado;  and  the  Plants  by  Dr.  Arthur  Hollick  of 
Columbia  University,  New  York.  Mr.  Charles  Schuchert  of  the  U.  S. 
National  Museum  has  revised  the  descriptions  of  the  Brachiopoda. 

Extensive  collections  of  material  were  made  preparatory  to  this  work, 
and  all  the  leading  fossiliferous  localities  of  the  state  were  visited.  The 
greatest  amount  of  material  was  obtained,  however,  from  the  bluffs  along 
the  banks  of  the  Potomac  river,  which  afford  the  most  com})lete  section 
of  the  Eocene  in  the  Middle  Atlantic  Slope.  In  general,  the  fossils  of 
this  region  are  difficult  of  removal,  as  they  readily  crumble  at  the  touch, 
so  that  some  process  of  hardening  had  to  be  employed  to  preserve  them 
permanently.  To  this  fact  more  than  to  any  other  cause,  has  been  due 


MAEYLAND  GEOLOGICAL  SUKYEY 


17 


the  small  size  of  the  collections  of  Eocene  specimens  found  in  the  various 
museums  of  the  countr}',  as  compared  vdth  the  collections  of  Neocene 
forms  from  the  same  area.  The  forms  figured  and  described  in  this 
report  have  come,  with  scarcely  an  exception,  from  the  collections  of  the 
United  States  National  Museum,  the  Academy  of  Natural  Sciences  of 
Philadelphia,  the  Johns  Hopkins  University,  and  the  Maryland  Geo- 
logical Survey.  The  Museum  of  the  Academy  of  Natural  Sciences  of 
Philadelphia  contains  Dr.  Conrad’s  types,  which  have  been  most  im- 
portant in  definitely  determining  the  species  hitherto  described. 

The  State  Geological  Survey  desires  to  express  its  thanks  for  the  aid 
which  has  been  rendered  by  the  several  experts  who  have  contributed  to 
this  volume;  also  to  the  U.  S.  Geological  Survey  which  has  generously 
allowed  the  use  of  many  of  its  plates  and  drawings,  which  have  materially 
reduced  the  expenses  of  publication;  and  to  Professor  G.  D.  Harris  for 
the  loan  of  several  drawings. 

Many  important  suggestions  have  also  been  received  from  Dr.  W.  H. 
Dali  of  the  U.  S.  Geological  Survey,  Professor  H.  A.  Pilsbry  of  the 
Philadelphia  Academy  of  Natural  Sciences  and  Mr.  C.  W.  Johnson  of 
the  Wagner  Free  Institute  of  Science.  They  have  examined  many  of 
the  determinations  of  fossils,  and  have  thus  materially  contributed  to 
the  accuracy  of  the  report. 

Thanks  are  also  due  to  the  artists  Mr.  J.  C.  McConnell  of  the  U.  S. 
Army-Medical  Museum,  Mr.  H.  C.  Hunter  of  the  U.  S.  Geological  Sur- 
vey and  Mr.  F.  von  Person  for  the  beautiful  drawings  with  which  the 
report  is  illustrated. 


2 


THE  EOCENE  DEPOSITS 

OF  MARYLAND 


BY 


WILLIAM  BULLOCK  CLARK 

AND 

GEORGE  CURTIS  MARTIN 


MARYLAND  GEOLOGICAL  SURVEY 


EOCENE,  PLATE  I 


I 


* Fossil  Localities 

NOTE:  The  Nanjemoy  formation  is  divided  into  the  Wood- 

stock  member  which  consists  of  argillaceotis  greensands,  and  into 
the  Potapaco  member  which  is  composed  of  argillaceous  sands  above 
and  clays  below.  The  Aquia  formation  is  divided  into  the  Paspo- 
tansa  member  which  consists  of  ledges  of  greensand  marls  under- 
lain by  greensands,  and  the  Piscataway  member  which  is  composed 
of  inter  stratified  layers  of  indurated  greensand  marls  and  incoherent 
greensands. 


THE  EOCENE  DEPOSITS  OE  MARYLAND 


BY 

William  Bullock  Clark  and  George  Curtis  Martin 


Intkoduction. 

Maryland,  as  an  important  division  of  the  Atlantic  border  region, 
comprises  in  its  geology  and  mineral  resources  mnch  that  is  typical  of 
the  entire  province.  No  discussion  of  Maryland  geology,  therefore,  can 
be  regarded  as  complete  that  does  not  at  the  same  time  take  into  con- 
sideration the  formations  of  immediately  adjacent  states.  Mnch  may 
be  learned  in  this  way  that  will  be  of  advantage  in  interpreting  our  own 
geology,  since  geological  deposits  are  not  limited  by  political  boundaries. 

Maryland,  together  with  Delaware  and  Virginia,  forms  what  has  with 
propriety  been  termed  the  Middle  Atlantic  Slope,  and,  as  described 
in  the  earlier  volumes  of  the  Survey,  has  been  divided  into  the  Coastal 
Plain,  the  Piedmont  Plateau,  and  the  Appalachian  Kegion.  The  pres- 
ent report  is  confined  to  a consideration  of  only  a part  of  the  first  of 
these  divisions. 

Much  interest  has  been  manifested  in  the  Coastal  Plain  geology  and 
paleontology  of  the  Middle  Atlantic  Slope  since  the  early  days  of  geo- 
logical investigation  in  this  country.  Many  of  the  most  potent  illus- 
trations of  the  geologists  of  the  early  part  of  the  century  were  drawn 
from  this  region,  and  although  the  relations  of  the  deposits  were  not 
altogether  comprehended,  yet  the  recorded  observations  show  an  appre- 
ciation of  many  of  the  more  difficult  problems  involved.  Later,  as  the 
complicated  geological  history  of  the  Coastal  Plain  became  better  known, 
it  was  recognized  that,  if  a full  understanding  of  any  single  formation 
was  to  be  gained,  it  was  necessary  to  study  carefully  not  only  its  litho- 
logical and  paleontological  characteristics  but  also  its  relationship  to 


22 


THE  EOCENE  DEPOSITS  OF  MAEYLAND 


the  other  members  of  the  series.  It  was  seen  that  only  by  an  under- 
standing of  the  broad  conditions  affecting  the  whole  district  could  the 
strata  of  any  one  formation  be  properly  interpreted.  Eecognizing  this 
fact,  the  writers  present  in  later  pages  a brief  discussion  of  the  general 
relations  of  the  strata  composing  the  Coastal  Plain  in  the  Middle  At- 
lantic Slope.  The  fuller  discussions  will  be  found  in  the  later  volumes 
dealing  with  these  formations. 

When  we  come  to  consider  that  assemblage  of  deposits  (Eocene  and 
Neocene)  early  separated  as  the  Tertiary,  we  find  that  it  is  divisible  into 
several  distinct  formations.  Even  at  a relatively  early  date  an  older  and 
a younger  Tertiary  were  already  established,  the  former  being  corre- 
lated with  the  Eocene  of  England  and  the  European  continent.  At- 
tempts were  made  then  and  later  to  find  its  exact  equivalent  in  one  or 
another  of  the  already  established  local  formations  of  the  English  or 
continental  series,  but  with  very  unsatisfactory  results. 

After  the  American  Eocene  strata  had  received  somewhat  detailed 
examination  in  the  various  sections  of  the  country  and  local  divisions 
had  been  established,  attempts  were  made  from  time  to  time  to  deter- 
mine their  equivalency.  By  common  consent  the  diversified  and  exten- 
sive deposits  of  the  Gulf  area  came  to  be  regarded  as  the  type  for  the 
eastern  border  region,  and  the  various  Eocene  deposits  of  the  Atlantic 
Coast  States  were  assigned  to  positions  in  this  series.  Some  authors, 
recognizing  the  presence  of  a few  identical  species,  have  referred  the 
strata  now  under  consideration  to  a single  minor  division  in  the  scale, 
while  others  have  regarded  the  Maryland-AGrginia  deposits  as  repre- 
senting a larger  portion  of  the  Gulf  series.  After  a careful  consideration 
of  both  the  paleontological  and  the  geological  data,  the  writers  deem 
the  latter  conclusion  the  only  tenable  one. 

Attention  has  been  devoted  in  the  past  too  exclusively  to  supposed 
faunal  similarities,  upon  the  most  insufficient  knowledge  of  the  forms, 
and  too  little  to  the  character  of  the  sedimentation.  Important  as  the 
former  are  when  the  fauna  has  been  fully  investigated,  and  the  writers 
would  be  far  from  disparaging  that  importance,  yet  the  widely  different 
physical  conditions  surrounding  the  accumulation  of  the  deposits  in  the 
two  areas  must  at  the  same  time  be  regarded.  Change  in  a fauna  is 


MAE'S  LAXD  GEOLOGICAL  SURVEA' 


23 


not  to  be  measured  by  tlie  time  standard  alone,  but  also  by  the  condi- 
tions of  life,  whether  constant  or  variable,  to  which  the  forms  may  be 
subjected.  Persistent  conditions  must  of  necessity  have  less  effect  than 
those  which  are  changing.  A satisfactory  correlation  of  the  strata  in 
districts  so  widely  separated  as  the  Middle  Atlantic  Coastal  Plain  and 
the  Gulf  Region  can  be  attained  only  by  a proper  appreciation  of  the 
bearing  of  these  factors  on  faunal  development. 

In  the  Middle  Atlantic  Slope  the  relatively  homogeneous  nature  of 
the  Eocene  deposits  is  a characteristic  feature,  indicating  that  through- 
out the  period  of  deposition  the  conditions  were  undisturbed  by  import- 
ant physical  changes.  The  fact  that  the  deposits  are  made  up  largely 
of  secondary  materials  shows  in  a general  way  that  their  accumulation 
took  place  near  a coast  reached  by  few  large  sediment-bearing  rivers,  and 
that  at  the  same  time  the  place  of  deposition  was  sufficiently  removed 
from  the  coast  line  to  be  unaffected  by  shore  conditions.  In*  the  Gulf 
Region,  on  the  other  hand,  deposition  was  more  rapid,  since  a great 
quantity  of  detrital  material  was  brought  to  the  sea  by  the  large  streams 
draining  the  interior  of  the  continent.  The  bearing  of  these  different 
physical  conditions  upon  the  interpretation  of  the  two  areas  and  the 
correlation  of  their  deposits  will  be  fully  considered  in  the  body  of  the 
report. 

The  materials  of  the  Eocene  of  the  Middle  Atlantic  Slope,  which  are 
so  largely  glauconitic,  are  of  no  little  interest  in  themselves  outside  of 
their  bearing  ujion  the  questions  of  correlation,  since  few  areas  afford 
such  extensive  deposits  of  greensand.  On  that  account  alone  they  de- 
serve special  consideration,  and  a chapter  will  be  devoted  to  this  phase 
of  the  subject. 

The  description  of  new  species  of  fossils  is  of  little  scientific  impor- 
tance to  the  geologist  unless  the  object  is  something  other  than  the 
mere  multiplication  of  new  forms,  which  has  too  often  been  the  case  in 
such  investigations.  AVhen,  however,  the  work  has  in  view  the  fullest 
possible  representation  of  a fauna  or  the  clearing  up  of  doubtful  points 
in  the  synonymy  of  already  described  species,  as  well  as  a more  complete 
knowledge  of  their  geological  and  geographical  ranges,  it  becomes  of 
the  very  greatest  value,  since  one  whole  class  of  important  criteria  for 


24 


THE  EOCENE  DEPOSITS  OF  MAEYLAND 


the  interpretation  of  the  strata  is  thus  made  accessible.  The  present 
report  includes  the  results  of  such  an  exhaustive  study  of  the  fauna  of 
the  Eocene  of  Maryland,  together  with  a critical  review  of  the  species 
described  by  previous  authors,  as  well  as  the  description  of  a large  num- 
ber of  new  forms.  It  is  believed  that  a much  more  accurate  idea  of  the 
faunal  characteristics,  as  well  as  of  the  physical  conditions  prevailing 
during  the  Eocene  period  on  the  Middle  Atlantic  Coast,  will  result  from 
the  methods  pursued  in  this  investigation.  Certainly  the  data  for  the 
comparison  of  the  fauna  with  those  of  other  areas  will  be  greatly  aug- 
mented. 

Histoeical  Eeyiew.^ 

On  account  of  its  extensive  waterways  and  the  ready  access  thereby 
gained,  the  Atlantic  Coastal  Plain  was  early  visited  for  purposes  of  geo- 
logical investigation.  At  first  the  observations  were  of  the  most  general 
character,  no  attempt  being  made  to  differentiate  the  deposits  or  even 
to  correlate  the  strata  as  a whole  with  those  of  other  districts. 

Among  the  earliest  investigators  of  the  region  was  Professor  Peter 
Kalm,  who  was  sent  out  in  1749  under  the  auspices  of  the  Swedish  Koyal 
Academy  of  Sciences  to  make  a study  of  the  various  branches  of  natural 
history  in  America,  and  who  spent  considerable  time  in  a study  of  the 
northern  Coastal  Plain. 

He  was  followed  in  1777  by  Dr.  Johann  David  Schopf,  of  Germany, 
who  visited  America  in  order  to  study  the  geological  features  of  the 
eastern  portion  of  the  continent.  The  importance  of  his  observations, 
which  mark  considerable  advance  over  those  of  Kalm,  has  not  been  very 
generally  recognized  by  later  writers,  but  he  showed  a remarkably  keen 
insight  into  the  geology  of  eastern  Korth  America,  which  was  lacking 
on  the  part  of  some  of  his  successors. 

The  first  attempt  to  correlate  the  deposits  of  the  eastern  United  States 
with  the  geological  column  then  established  in  Europe  was  made  by 
William  Maclure,  in  1809,  in  his  Observations  upon  the  Geology  of  the 

1 Both  in  this  and  in  the  subsequent  chapter,  comprising  the  Bibliography,  refer- 
ences are  made  to  articles  and  books  dealing  also  with  the  Eocene  of  Delaware  and 
Virginia  since  the  deposits  are  embraced  in  the  same  geologic  province  with  those  of 
Maryland. 


MARYLAND  GEOLOGICAL  SURVEY^ 


25 


United  States.  In  this  publication  the  coastal  deposits  of  the  Middle 
Atlantic  Slope  are  collectively  referred  to  the  Alluvial  formation/’  the 
fourth  of  the  main  divisions  of  geological  strata  originally  proposed  hy 
Werner.  The  work  was  subsequently  revised  and  enlarged,  appearing  in 
book  form  in  1817.* 

In  1820  II.  H.  Hayden,  of  Baltimore,  published  a volume  of  Geological 
Essays,  in  which  he  attempted  to  explain  the  great  accumulation  of 
alluvial  deposits”  in  the  Atlantic  Coastal  Plain.  In  this  volume  the 
stratigraphy  of  the  region  is  described  in  much  greater  detail  than  by 
his  predecessors,  and  reference  is  made  to  the  wide  distribution  of  fossil 
shells  and  vertebrate  remains,  many  localities  being  cited. 

A volume  of  the  same  character,  so  far  as  it  relates  to  the  geology,  was 
published  in  1822  by  Parker  Cleaveland,  entitled  an  Elementary  Trea- 
tise on  Mineralogy  and  Geology,  in  which,  on  page  785,  under  remarks 
on  the  Geology  of  the  United  States  explanatory  of  the  subjoined 
geological  map,”  the  limits  and  the  lithological  character  of  the  allu- 
vial deposits  ” are  described  in  general  terms. 

By  far  the  most  important  contribution  to  the  stratigraphy  of  the 
Atlantic  Coastal  Plain  that  had  up  to  that  time  appeared  was  made  by 
Professor  John  Finch,  in  a “ Geological  essay  on  the  Tertiary  formations 
in  America,”  in  the  American  Journal  of  Science  and  Arts  for  1824. 
This  was  the  first  attempt  at  a division  of  the  deposits  of  the  Coastal 
Plain  and  their  correlation  upon  scientific  grounds;  and  although  thus 
early  in  the  history  of  the  subject  detailed  comparisons  (which  are 
always  unsatisfactory)  were  made,  yet  the  knowledge  of  the  formations 
was  materially  advanced.  The  author  says: 

In  America  an  immense  tract  of  country,  extending  from  Long  Island  to  the  Sea 
of  Mexico,  and  from  30  to  200  miles  in  width,  is  called  an  alluvial  formation.  From 
an  examination  of  fossils  brought  from  that  quarter  of  the  United  States,  from  a 
personal  inspection  of  some  of  its  strata,  and  the  perusal  of  most  of  the  publications 
which  bear  a reference  to  it,  I wish  to  suggest  that  what  is  termed  the  alluvial  for- 
mation in  the  geological  maps  of  Messrs.  Maclure  and  Cleaveland  is  identical  and  con- 
temporaneous with  the  newer  Secondary  and  Tertiary  formations  of  France,  England, 
Spain,  Germany,  Italy,  Hungary,  Poland,  Iceland,  Egypt  and  Ilindostan. 

The  deposits  of  various  portions  of  the  Middle  Atlantic  Slope  are 
considered  in  greater  or  less  detail,  and  correlations  with  the  strata  of 


26 


THE  EOCENE  DEPOSITS  OF  MAKYLAND 


other  portions  of  the  Coastal  Plain  and  with  Europe  are  attempted.. 
The  author  states  in  short  that — 

Many  more  instances  might  be  advanced  to  establish  the  identity  of  what  has  been 
called  the  alluvial  district  in  America  with  the  Tertiary  formation  of  England  and  the 
continent  of  Europe.  The  fossil  shells  from  the  various  beds  would  not,  perhaps,  be 
exactly  like  those  of  Europe,  but  a sufficient  number  would  be  found  so  to  establish 
their  relation  and  order  of  succession. 

During  the  year  1825  Jer.  Van  Eensselaer  delivered  in  the  New  York 
Athenaeum  a course  of  geological  lectures  that  were  subsequently  pub- 
lished in  book  form.  The  author  adopted  the  classification  proposed 
by  Einclq  confining  his  descriptions,  however,  more  particularly  to  the 
formations  of  the  northern  Coastal  Plain. 

The  American  Journal  of  Science  for  1826  contains  a communication 
by  James  Pierce  On  the  shell-marl  region  of  the  eastern  parts  of  Vir- 
ginia and  Maryland,’’  in  which  reference  is  made  to  the  sections  on  the 
James  and  Potomac  rivers  and  to  the  shell  rock  ” at  Upper  Marlboro. 

A few  years  later  (1828)  Professor  Lardner  Vanuxem,  through  his 
friend,  Dr.  S.  G.  Morton,  presented  the  criteria  for  a more  complete  and 
definite  recognition  of  the  several  members  of  the  coastal  series,  and 
described  both  the  Cretaceous  and  Tertiary  formations.  In  this  article 
an  attempt  is  made  to  define  more  accurately  the  limits  of  the  Tertiary. 
The  author  states  that  much  that  had  been  designated  by  that  name 
properly  belongs  to  other  formations. 

Up  to  the  year  1830  all  investigations  of  the  stratigraphy  of  the  Ter- 
tiary had  been  carried  on  in  the  main  independently  of  a study  of  the 
fossils.  Generic  identity  had  been  cited  as  ground  for  correlation,  and 
although  this  aided  largely  in  determining  the  limits  of  the  Tertiary 
itself,  further  subdivisions  were  impracticable. 

The  publication  of  Conrad’s  article  On  the  geology  and  organic  re- 
mains of  a part  of  the  peninsula  of  Maryland,”  with  an  appendix  con- 
taining descriptions  of  new  species  of  fossil  shells,  inaugurated  a new 
era  in  the  investigation  of  the  Coastal  Plain  strata.  It  is  true  that  Say 
had  already  described  several  Tertiary  species,  including  the  common 
Ostrea  compressirosira  of  the  Eocene  of  the  Middle  Atlantic  Slope,  but, 
as  stated  in  Conrad’s  paper,  he  did  not  draw  any  geological  inferences 


MARYLAND  GEOLOGICAL  SURVEY 


27 


from  the  organic  remains  examined.”  Conrad  from  the  first  applied 
the  paleontological  evidence  he  had  acquired  to  an  interpretation  of  the 
stratigraphy;  and,  although  many  of  his  conclusions  were  erroneous,  the 
knowledge  of  the  geology  of  the  Coastal  Plain  was  very  materially  ad- 
vanced hy  his  work.  In  this  first  paper  such  well-known  early  Ter- 
tiary forms  as  Turritella  mortoni,  CucuUaea  gigantea,  and  Crassatella 
alaeformis  are  figured  and  described,  while  the  presence  of  Venericardia 
planicosta  Lamarck  is  also  noted.  By  the  use  of  the  data  afforded  hy 
these  investigations  the  strata  at  Fort  Washington,  were  correlated  with 
the  London  Clay  of  England. 

In  1832  Conrad  began  the  publication  (in  parts)  of  an  important 
work  entitled  Fossil  shells  of  the  Tertiary  formations  of  North 
America.”  This  and  its  companion  volume  upon  the  “ Middle  Ter- 
tiary,” commenced  some  years  later,  must  he  regarded  as  the  basis  of  all 
later  work  upon  American  Tertiary  paleontology.  In  the  earlier  publi- 
cation Conrad  regarded  the  deposits  in  the  vicinity  of  Fort  Washington, 
as  Middle  Tertiary,”  and  correlated  them  with  the  London  Clay  and 
Calcaire  grassier  of  Europe,  and  the  Claiborne  beds  of  Alabama. 

Before  the  completion  of  Conrad^s  first  work  above  mentioned  Lea 
published  his  Contributions  to  geology,”  in  which  a large  number  of 
Eocene  fossils  are  described  and  the  stratigraphy  of  the  Tertiary  of  the 
Atlantic  Coastal  Plain  is  discussed.  In  this  work  the  term  Eocene  is 
first  applied  to  the  American  Lower  Tertiary  deposits,  although  the 
general  position  of  the  deposits  had  already  been  recognized  hy  Conrad. 
The  latter,  however,  in  1834,  in  his  Observations  on  the  Tertiary  and 
more  recent  formations  of  a portion  of  the  Southern  States,”  employs 
the  term  Eocene  for  the  Eort  Washington  deposits,  although  he  there 
regards  them  as  younger  than  the  Claiborne  beds,  and  even  suggests 
their  Miocene  age. 

During  the  same  year  Professor  William  B.  Eogers  made  his  first  con- 
tribution to  the  Eocene  geology  of  Virginia,  and  although  this  article 
contained  little  of  real  importance,  it  is  of  interest  as  being  the  first  of 
a series  of  important  publications  upon  the  geology  of  Virginia. 

Dr.  S.  G.  Morton,  whose  investigations  were  chiefly  confined  to  the 
Cretaceous,  gives  in  his  Synopsis,  etc.,”  published  at  this  time,  a 


28 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


Catalogue  of  the  fossil  shells  of  the  Tertiary  formations  of  the  United 
States/^  in  which  many  of  the  Middle  Atlantic  Slope  forms  are  included. 

During  the  year  1835  several  important  contributions  were  made  to 
the  geology  of  the  Atlantic  Tertiary  region.  Conrad  published  his  in- 
vestigations upon  the  IMaryland-A^irginia  Tertiary  area,  including  the 
description  of  two  new  species  of  Eocene  fossils.  Eogers  presented 
“Further  observations  on  the  greensand  and  calcareous  marl  of  Vir- 
ginia,in  which  the  lithological  similarity  of  the  beds  to  the  greensand 
deposits  of  New  Jersey  is  dwelt  upon,  although  he  believes  that  the 
character  of  the  organic  remains  shows  the  strata  to  be  Eocene.  Jointly 
with  his  brother,  H.  D.  Eogers,  he  presented  to  the  Philadelphia  Acad- 
emy of  hTatural  Sciences  the  first  portion  of  “ Contributions  to  the  geol- 
ogy of  the  Tertiary  formations  of  Virginia,’’  in  which  several  new 
species  of  Eocene  fossils  are  described. 

While  the  investigations  hitherto  mentioned  were  being  carried  on 
privately,  the  three  states  constituting  that  portion  of  the  Middle  At- 
lantic Slope  now  under  consideration,  viz.,  Delaware,  Maryland,  and 
Virginia,  became  aroused  to  the  importance  of  official  geological  surveys 
of  their  areas. 

The  first  to  organize  such  a survey  was  Maryland,  in  1833,  J.  T. 
Ducatel  being  appointed  State  Geologist.  Eeports  were  published  until 
1841,  but  the  information  they  contain  is  economic  rather  than  strati- 
graphic. 

The  Geological  Survey  of  Virginia  began  operations  in  1835,  under 
William  B.  Eogers  as  State  Geologist,  who  was  thus  able  to  continue 
much  more  systematically  than  hitherto  his  observations  upon  the  Ter- 
tiary belt.  The  first  report,  for  1835,  which  contains  a general  state- 
ment regarding  the  “ Eocene  marl  district,”  and  most  of  the  subsequent 
annual  reports,  which  were  continued  until  1841,  include  more  or  less 
detailed  descriptions  of  the  Eocene  deposits.  Collectively  they  form 
the  chief  source  of  information  regarding  the  Eocene  stratigraphy  of 
Virginia. 

The  Geological  Survey  of  Delaware  was  short  lived.  Its  investiga- 
tions, under  the  direction  of  I.  C.  Booth,  State  Geologist,  extended  only 
over  the  seasons  1837  and  1838,  for  which  years  annual  reports  were 


MAEYLAXD  GEOLOGICAL  SUEVEY 


29 


published,  and,  in  addition,  a more  exhaustive  ‘^Memoir’’  in  1841;  bnt 
in  none  of  these  jmblications  was  the  Eocene  recognized  as  such. 

Conrad,  who  actively  continued  his  investigations,  made  an  import- 
ant contribution  to  the  Eocene  of  the  Middle  Atlantic  Slope  in  1842 
in  his  Observations  on  a portion  of  the  Atlantic  Tertiary  region,  with 
a description  of  new  species  of  organic  remains.” 

During  this  year  the  first  of  Lyell’s  pnblications  npon  the  eastern 
Tertiary  belt  appeared  in  the  Proceedings  of  the  Geological  Society  of 
London.  His  conclusions  were  derived  from  personal  observations,  and 
were  of  special  value  from  his  wide  knowledge  of  the  Tertiary  of 
Europe.  He  succeeded  in  explaining  many  points  in  American  Tertiary 
stratigraphy  hitherto  imperfectly  understood.  The  narrative  of  his 
first  report  contains  the  following  statement: 

Having  examined  the  most  important  Cretaceous  deposits  in  New  Jersey,  Mr. 
Lyell  proceeded  in  the  autumn  of  1841  to  investigate  the  Tertiary  strata  of  Virginia, 
the  Carolinas,  and  Georgia,  with  a view  to  satisfy  himself,  first,  how  far  the  leading 
divisions  of  Tertiary  strata  along  the  Atlantic  border  of  the  United  States  agree  in 
aspect  and  organic  contents  with  those  of  Europe;  and,  secondly,  to  ascertain 
whether  any  rocks  containing  fossils  of  a character  intermediate  between  those  of 
the  Cretaceous  and  the  Eocene  beds  really  exist.  The  conclusions  at  which  he 
arrived  from  his  extensive  survey  are  given  briefly  as  follows : (1)  The  only  Tertiary 
formations  which  the  author  saw  agree  well  in  their  geological  types  with  the  Eocene 
and  Miocene  beds  of  England  and  France;  (2)  he  found  no  secondary  fossils  in  those 
rocks  which  have  been  called  Upper  Secondary  and  supposed  to  constitute  a link 
between  the  Cretaceous  and  Tertiary  formations. 

The  Eocene  deposits  upon  the  James  Eiver,  Virginia,  are  described 
in  this  paper.  In  his  subsequent  papers  bearing  upon  the  Eocene  of 
the  Middle  Atlantic  Slope  the  stratigraphy  of  the  Eocene  is  further 
considered  and  references  are  made  to  other  localities  which  he  visited. 

Murchison,  in  his  presidential  address  before  the  Geological  Society 
of  London  in  1843,  reviewed  the  results  of  LyelFs  investigations  in 
America  and  added  his  own  interpretation  of  a few  points. 

During  the  years  immediately  subsequent  to  LyelTs  visit  many  im- 
portant articles  upon  the  Tertiary  appeared  from  the  pens  of  American 
geologists,  although  the  publications  dealt  more  largely  with  the  south- 
ern than  the  northern  deposits.  Conrad,  however,  made  additional 
observations  upon  the  Eocene  strata  of  the  Middle  Atlantic  Slope  and 


30 


THE  EOCENE  DEPOSITS  OE  MAEYLAND 


described  a number  of  new  species.  About  this  time  Henry  C.  Lea  pub- 
lished a Catalogue  of  the  Tertiary  Testacea  of  the  United  States/'  in 
which  the  Middle  Atlantic  Slope  forms  are  included. 

Subsequent  to  1850  interest  in  the  Tertiary  geology  of  the  Middle 
Atlantic  Slope  seems  for  a time  to  have  waned,  and  during  the  next 
twenty-five  years  very  few  investigations  were  carried  on  within  the  dis- 
trict. In  Maryland  two  surveys,  partly  of  a geological  but  more  largely 
of  an  agricultural  nature,  were  inaugurated,  the  first,  under  James  Hig- 
gins, producing  six  reports  between  1850  and  1858,  and  the  second 
under  Philip  T.  Tyson,  who  presented  two  reports  in  1860  and  1862. 
In  the  report  for  1860  the  Tertiary  is  described  in  some  detail,  although 
no  attempt  is  made  to  establish  the  limits  of  its  several  divisions. 

Conrad  continued,  however,  to  carry  on  his  investigations  upon  the 
Atlantic  Tertiary  belt,  adding  to  the  number  of  new  fossil  forms  and 
publishing  two  catalogues  of  species. 

During  the  last  twenty-five  years,  and  particularly  in  the  latter  part 
of  this  period,  many  more  contributions  have  been  made  to  the  geology 
of  the  Middle  Atlantic  Slope.  Among  those  who  have  given  the  subject 
attention  may  be  mentioned  McGee,  Heilprin,  Darton,  Uhler,  Shattuck,. 
Bibbins,  Harris  and  the  authors  of  this  report.  To  the  publications  of 
McGee  we  are  indebted  more  than  to  any  other  for  a general  statement 
of  Coastal  Plain  conditions.  Although  some  modifications  have  been 
deemed  necessary  after  a detailed  study  of  the  formations,  the  writers 
are  impressed,  from  a careful  examination  of  large  portions  of  the  area, 
with  the  general  correctness  of  the  broad  principles  enunciated  by  him. 
Heilprin  has  devoted  considerable  attention  to  Atlantic  Coast  paleon- 
tology, comparing  several  of  the  Eocene  species  of  Maryland  and  Vir- 
ginia with  European  forms,  and  correlating  the  strata,  as  a result  of 
these  investigations,  with  the  lower  members  of  the  English  and  French 
series.  Both  Darton  and  Uhler  have  studied  the  local  relations  of  the 
Eocene  deposits,  the  former  having  prepared  several  United  States  Geo- 
logical Survey  atlas  sheets  of  the  central  and  southern  portions  of  the 
district. 

Others  have  turned  their  attention  from  time  to  time  to  the  area,  and 
from  their  knowledge  of  other  districts  have  aided  to  a greater  or  less 


MAKYLAND  GEOLOGICAL  SUEVEY 


31 


degree  in  interpreting  the  geology  of  the  Eocene  of  Maryland.  The 
articles  contributed  by  all  the  various  workers  in  this  field  are  given  in 
the  bibliography. 


Bibliography. 

Aldrich,  T.  H.  x^otes  on  Eocene  Mollnsca. 

Bull.  Amer.  Pal.,  vol.  ii,  No.  8. 

Crassetalla  declivis  Heilprin  and  Ringicula  dalli  Clark  are  figured. 

Bagg,  K.  M.  Jr.  Contributions  to  the  Eocene  fauna  of  the  Middle 
Atlantic  Slope.  Protozoa. 

Johns  Hopkins  Univ.  Circ.,  vol.  xv,  1895,  p.  6. 

Spiroplecta  clarki  is  described  from  Woodstock,  Virginia. 

The  Eocene  Deposits  of  the  Middle  Atlantic  Slope  in  Dela- 
ware, Maryland  and  Virginia.  Protozoa. 

Bull.  141,  U.  S.  Geol.  Surv65%  1896,  pp.  91,  92. 

A list  of  Eocene  Foraminifera  is  given. 

The  Tertiary  and  Pleistocene  Foraminifera  of  the  Middle  At- 
lantic Slope. 

Bull.  Amer.  Pal.,  vol.  ii,  No.  10,  1898,  pp.  295-348  (1-34),  pis.  xxi-xxiii  (i-iii). 

Several  Eocene  species  are  figured  and  described. 

The  occurrence  of  Cretaceous  fossils  in  the  Eocene  of  Mary- 
land. 

Amer.  Geol.,  vol.  xxii,  1898,  pp.  370-375. 

The  author  mentions  the  occurrence  of  Terebralula  liarlani  and  Gryphaea  vesicularis 
in  the  Maryland  Eocene. 

Bailey,  J.  W.  htotice  of  some  New  Localities  of  Infusoria,  Fossil 
and  Eecent. 

Amer.  Jour.  Sci.,  vol.  xlviii,  1845,  pp.  321-343,  pi.  iv. 

Mentions  occurrence  of  casts  “ in  some  of  the  Eocene  marls  from  Fort  Washington.” 

On  the  Origin  of  Greensand,  and  its  formation  in  the  oceans 

of  the  present  epoch. 

Amer.  Jour.  Sci.,  2nd  ser.,  vol.  xxii,  1856,  pp.  280-284. 

Proc.  Bost.  Soc.  Nat.  Hist.,  vol.  v,  pp.  364-368. 

Author  again  refers  to  “ casts  ” found  in  Fort  Washington  Eocene. 

Bassler,  Pay  S.  and  Nickles,  John  M.  A Synopsis  of  American 
Fossil  Bryozoa. 

Bull.  173,  U.  S.  Geol.  Survey,  1900,  p.  72. 

Upper  Marlboro  is  included  in  the  list  of  Eocene  localities. 


32 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


Booth,  J.  C.  Memoir  of  the  Geological  Survey  of  the  State  of  Dela- 
ware, including  tlie  application  of  the  geological  observations  to  agri- 
culture. 

Dover,  1841,  8vo,  xi  and  188  pp. 

The  author  gives  a description  of  tlie  Upper  Secondarj^  and  Tertiary  formations,  hut 
does  not  distinguish  the  Eocene. 

Clark,  William  Bullock.  On  three  geological  excursions  made 
during  the  months  of  October  and  November,  1887,  into  the  southern 
counties  of  Maryland. 

Johns  Hopkins  Univ.  Circ.,  vol.  vii,  1888,  pp.  65-67. 

Reference  is  made  in  this  article  to  the  Eocene  of  Upper  Marlboro  and  Port 
Tobacco. 

Third  annual  geological  expedition  into  southern  Maryland 

and  Virginia. 

Ibid.,  vol.  ix,  1890,  pp.  69-71. 

The  author  describes  the  Eocene  section  of  the  Potomac  river  valley  in  Maryland 
and  Virginia. 

Eeport  of  the  scientific  expedition  into  southern  Maryland. 

Ibid.,  vol.  X,  1891,  pp.  105-109. 

Much  of  the  same  areas  are  described  in  this  report  as  in  the  preceding  paper. 

Correlation  Papers — Eocene. 

Bull.  83,  U.  S.  Geol.  Survey,  1891,  pp.  43-48,  80,  81,  85-87. 

The  author  gives  a digest  of  the  literature  of  the  Eocene  of  the  Middle  Atlantic 
Slope,  as  well  as  a description  of  the  deposits.  Correlation  is  made  with  the  lower  and 
middle  divisions  of  the  Gulf  series. 

Outline  of  the  geology  and  physical  features  of  Maryland. 

The  Eocene. 

In  Maryland,  its  Resources,  Industries  and  Institutions,  Baltimore,  1893, 
pp.  53-56. 

In  this  report  the  author  gives  a brief  description  of  the  Eocene  deposits  of  Maryland. 

The  climatology  and  physical  features  of  Maryland. 

First  Biennial  Report  Md.  State  Weather  Service,  1894,  pp.  38-39. 

Description  of  the  same  area  as  in  the  preceding  report. 

Contributions  to  the  Eocene  fauna  of  the  Middle  Atlantic 

Slope. 

Johns  IIoj)kins  Univ.  Circ.,  vol.  xv,  1895,  x^p.  3-6. 

This  article  contains  a list  and  discussion  of  the  Eocene  species  of  Delaware,  Mary- 
land and  Virginia,  with  the  description  of  32  new  forms.  The  part  upon  Corals  is  pre- 
pared by  Vaughan,  that  upon  Foraminifera  by  Bagg. 

The  Potomac  Eiver  Section  of  the  Middle  Atlantic  Coast 

Eocene. 

Am.  Jour.  Sci.,  4th  ser.,  vol.  i,  1896,  x^p.  365-374. 

A detailed  section  of  the  Botomac  river  section  is  given. 


MARYLAXD  GEOLOGICAL  SUKVEY 


33 


The  p]ocene  Deposits  of  the  iMiddle  Atlantic  Slope  in  Dela- 
ware, Maryland  and  Virginia. 

Bull.  141,  U.  S.  Geol.  Survey,  1896,  167  j)p.  40  plates. 

A general  discussion  of  the  geological  features,  distribution,  character  and  correlation 
of  the  deposits,  with  a description  of  the  contained  fossils.  A number  of  new  species 
are  added. 

Outline  of  present  knowledge  of  the  Physical  Features  of 

Maryland,  embracing  an  account  of  the  Physiography,  Geology,  and 
Mineral  Eesources. 

Md.  Geol.  Survey,  vol.  i,  1897,  pp.  195,  196,  217. 

The  Eocene  deposits  of  the  state  are  described. 

Collection  of  Eocene  Fossils. 

Johns  Hopkins  Univ.  Circ.,  vol.  xviii,  1898,  No.  137,  p.  18. 

The  author  substitutes  the  name  Pecten  dalli  for  Pecten  ro(jersi  which  was  already 
pre-empted. 

Cleavelaxd,  Parkek. — An  elementary  treatise  on  mineralogy  and 
geology.  Pemarks  on  the  geology  of  the  United  States  explanatory  of 
the  subjoined  geological  map,  Boston,  1822,  785  ])]l 

The  author  defines  the  limits  of  the  “ alluvial  deposits  ” and  in  general  terms 
describes  their  lithological  character. 

CoxRAD,  T.  A.  On  the  geology  and  organic  remains  of  a part  of  the 
peninsula  of  Maryland. 

Jour.  Acad.  Nat.  Sci.,  Bhila.,  vol.  vi,  1830,  pp.  205-217. 

Reference  is  made  to  the  deposits  of  Fort  Washington  and  IMscataway,  and  correla- 
tion proposed  with  London  Clay  of  England.  The  paper  also  contains  original  descrip- 
tions of  Mouodonta  (jlaruhda,  TurriteUa  mortnni,  Cucullata  (jUfcintca,  and  Craxmtella 
alaeformifi  from  this  region. 

^ — Fossil  shells  of  the  Tertiary  formations  of  North  America, 

1832-1835,  56  pp.  (including  republication  No.  3),  20  pis. 

The  author  regards  the  deposits  in  the  vicinity  of  Fort  Washington  as  “ Middle 
Tertiary,”  and  correlates  them  with  the  London  Clay,  Calcaire  {jrosnier  and  Claiborne 
beds.  He  also  describes  Cardita  planicoi^ta  and  TurriteUa  mortoni  from  Piscataway. 

Observations  on  the  Tertiary  and  more  recent  formations  of 

a portion  of  the  Southern  States. 

Jour.  Acad.  Nat.  Sci.,  Bhila.,  vol.  vii,  1834,  pp.  116-129. 

Mention  is  made  of  the  deposits  of  Fort  IVashington,  which  are  considered  younger 
than  the  strata  at  Claiborne,  Ala.,  perhaps  Miocene  in  age. 

Observations  on  the  Tertiary  Strata  of  the  Atlantic  Coast. 

Amer.  Jour.  Sci.,  vol.  xxviii,  1835,  pp.  104-111. 

Author  states  that  there  are  no  Eocene  species  common  to  the  Pliocene. 

Observations  on  a portion  of  the  Atlantic  Tertiary  region. 

Trans.  Pennsylvania  Geol.  Soc.,  vol.  i,  1835,  pp.  335-341,  pi.  xiii. 

The  deposits  at  Upper  Marlboro  and  Piscataway,  and  City  Point,  Va.,  are  considered, 
and  Panopaea  elomjata  and  TurriteUa  humerom,  from  Piscataway  described. 

3 


34 


THE  EOCENE  DEPOSITS  OF  MAEYLAXD 


Notes  on  American  Geology.  Observations  on  characteristic 

Fossils,  and  upon  a fall  of  Temperature  in  different  geological  epochs. 

Amer.  Jour.  Sci.,  vol.  xxxv,  1839,  pp.  237-251. 

Refers  to  the  Eocene  deposits  of  Upper  Marlboro  and  Piscataway  as  illustrations  of 
deposition  by  gentle  currents. 

On  the  Silurian  system,  with  a table  of  the  strata  and  char- 
acteristic fossils.  Observations  on  the  Plastic  Clay. 

Amer.  Jour.  Sci.,  vol.  xxxviii,  1840,  pp.  91-92. 

The  authors  discusses  the  relations  of  the  Plastic  Clay  to  the  fossiliferous  deposits 
at  Piscataway,  which  it  is  regarded  in  some  instances  to  overlie. 

Observations  on  a portion  of  the  Atlantic  Tertiary  region, 

with  a description  of  new  species  of  organic  remains. 

Proc.  Nat.  Inst.  Prom.  Sci.,  2nd  bull.,  1842,  pp.  171-194. 

The  deposits  of  Upper  Marlboro,  Piscataway  and  Fort  "Washington  are  referred  to 
the  Eocene  or  Lower  Tertiary,  and  at  the  same  time  correlated  with  the  London  Clay, 
CaLcaire  grassier,  Claiborne  beds,  etc.  The  author  also  describes  Ostrea  seUaeformis 
from  City  Point,  Va.,  and  Pholadoniya  marylandica  and  Pholas  petrosa  from  Piscataway. 

Observations  on  the  Eocene  formations  of  the  United  States, 

with  descriptions  of  species  of  shells,  etc.,  occurring  in  it. 

Amer.  Jour.  Sci.,  2nd  series,  vol.  i,  1846,  pp.  209-220,  395-405,  pis.  i-iv. 

The  article  contains  descriptions  of  Pholas  petrosa,  Pholadomya  marylandica,  Pan- 
opaea  elongata,  and  Crassatella  alaeformis  from  Piscataway,  and  Crassatella  palmula 
from  Upper  Marlboro. 

Observations  on  the  Eocene  formation  and  descriptions  of 

one  hundred  and  five  new  fossils  of  that  period  from  the  vicinity  of 
Vicksburg,  Mississippi.  With  appendix. 

Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iii,  1847,  pp.  280-299. 

The  author  regards  the  Fort  Washington,  Piscataway  and  Upper  Marlboro -deposits 
as  lower  Eocene. 

Observations  on  the  Eocene  formation  and  descriptions  of  105 

new  fossils  of  that  period  from  the  vicinity  of  Vicksburg,  Miss.  Appen- 
dix: Descriptions  of  new  Eocene  fossils  in  the  cabinet  of  Lardner 
Vannxem. 

Jour.  Acad.  Nat.  Sci.,  Phila.,  2nd  series,  vol.  i,  1848,  pp.  128-134,  pi.  xiv. 

The  author  considers  the  Maryland  and  Virginia  deposits  as  “ Lower  or  older 
Eocene  ” and  correlates  them  with  the  “ fossiliferous  sand  of  Claiborne  and  St.  Steph- 
ens, Ala.,”  etc.,  chiefly  from  the  presence  of  0.  seUaeformis.  He  also  describes 
CyLherea  subimpressa,  C.  lenis,  C.  liciata.  C.  eversa,  and  Nucula  improcera  from  Hanover 
County,  Va. ; Cytherea  pyga  from  Stafford  County,  Va.,  and  Nucula  parilis  from  Upper 
Marlboro. 


Notes  on  Shells. 

Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  vi,  1853,  p.  320. 

Cytherea  lenticularis  Rogers  is  referred  to  the  genus  Artemis  of  Poli. 


MARYLAND  GEOLOGICAL  SURVEY 


35 


Eectification  of  the  generic  names  of  Tertiary  Fossil  Shells. 

Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  vii,  1854,  pp.  29-31. 

The  generic  names  of  .several  Ik>cene  fossils  from  Maryland  and  Virginia  are  changed. 

Xotes  on  shells,  with  descriptions  of  new  fossil  genera  and 

species. 

Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  xvi,  1864,  pp.  211-214,  with  figures. 

Descriptions  are  given  in  this  article  of  Protocardia  virginiana  from  Pamunkey 
River,  Va.,  and  DoniniopsiK  meehii  from  6 miles  east  of  AVashington,  D.  C.” 

Catalogue  of  the  Eocene  and  Oligocene  Testacea  of  the  United 

States. 

Amer.  .Tour.  Conch.,  vol.  i,  1865,  pp.  1-35. 

Among  other  forms  the  catalogue  contains  a list  of  the  Eocene  species  of  the  Middle 
Atlantic  Slope. 

Descriptions  of  new  Eocene  shells  and  references,  with  fig- 
ures, to  published  species. 

Ibid.,  pp.  210-212,  pis.  xx,  xxi. 

The  author  describes  Lunalia  rnarylandica,  but  gives  no  locality. 

Check  list  of  the  invertebrate  fossils  of  Xorth  America 

(Eocene  and  Oligocene). 

Smithsonian  ^lisc.  Coll.,  vol.  vii,  1866,  art.  6,  pp.  1-41. 

The  Eocene  species  from  the  Middle  Atlantic  Slope  are  included  in  this  list. 

Descriptions  and  illustrations  of  genera  of  shells. 

Proc.  Acad.  Nat.  Sci.  Phila.,  1872,  pp.  50-55. 

The  author  describes  Latiarca  idonea,  but  gives  no  locality. 

Dale,  VC.  H.  Contributions  to  the  Tertiary  Fauna  of  Florida,  etc. 

Trans.  AVagner  Free  Inst.  Sei.,  vol.  iii,  pts.  i-v,  1890-1900,  pp.  1-947. 

The  biological  and  geological  relations  of  many  of  the  Maryland  and  A'irginia  Eocene 
molluscan  species  are  discussed. 

A Table  of  the  Xorth  American  Tertiary  Horizons  correlated 

Avith  one  another  and  Avith  those  of  Western  Europe,  Avith  annotations. 

18th  Ann.  Kept.  U.  S.  Geol.  Survey,  1898,  pt.  ii,  pp.  325-348. 

The  Aiaryland  Eocene  is  briefly  discussed. 

Dana,  James  D.  Manual  of  Geology  (fourth  edition),  1895,  p.  888. 

Brief  reference  is  made  to  the  geologj*  of  the  Middle  Atlantic  Slope. 

Darton,  X.  H.  ^lesozoic  and  Cenozoic  formations  of  eastern  Vir- 
ginia and  Maryland. 

Bull.  Geol.  Soc.  Amer.,  vol-.  ii,  1891,  pi.  x,  pp.  431-450. 

The  author  gives  a description  of  the  Eocene  deposits  of  Maryland  and  ATrginia,  and 
designates  them  the  “ Pamunkey  formation.” 


36 


THE  EOCEXE  DEPOSITS  OF  MARYLAND 


Outline  of  Cenozoic  history  of  a portion  of  the  Middle  At- 
lantic Slope. 

Jour,  of  Geol.,  vol.  ii,  1894,  pp.  568-587. 

The  physical  history  during  the  Eocene  period  is  briefly  referred  to,  and  the  relation- 
ship of  the  deposits  to  earlier  and  later  formations  is  stated. 

Artesian  well  prospects  in  eastern  Virginia,  Maryland,  and 

Delaware. 

Trans.  Amer.  Inst.  Min.  Eng.,  vol.  xxiv,  1894,  pp.  372-379. 

The  lithological  character  of  the  strata  is  discussed  and  several  deep  borings  are 
described. 

Fredericksburg  Folio,  Virginia  and  Maryland. 

U.  S.  Geol.  Survey,  Geol.  Atlas,  folio  13,  Washington,  1894. 

The  author  describes  the  Eocene  deposits  of  the  area. 

Artesian  Well  Prospects  in  the  Atlantic  Coastal  Plain  Eegion. 

Bull.  138,  U.  S.  Geol.  Survey,  1896,  228  pp.,  19  plates. 

Numerous  Eocene  sections  are  given. 

Nomini  Folio,  Maryland  and  Virginia. 

U.  S.  Geol.  Survey,  Geol.  Atlas,  folio  23,  Washington,  1896. 

The  author  describes  the  Eocene  deposits  of  the  area. 

Ducatel,  J.  T.  Annual  reports  of  the  geologist  of  Maryland  from 
1833  to  1841. 

Annapolis,  8vo. 

Only  brief  references  to  Eocene  deposits,  and  those  chiefly  of  an  economic  nature, 
are  found  scattered  through  the  reports. 

Featherstonhaugh,  G.  W.  Geological  Eeport  of  an  examination 
made  in  1834  of  the  Elevated  Country  between  the  Missouri  and  Eed 
Eivers. 

Washington,  1835,  8vo,  97  pp. 

The  author  refers  to  the  Eocene  deposits  of  ^Maryland,  especially  the  fossil  if  erous 
beds  at  Fort  Washington  and  correlates  them  with  “ Lyell’s  Eocene.” 

Finch,  John.  Geological  essay  on  the  Tertiary  formations  in 
America. 

Amer.  Jour.  Sci.,  vol.  vii,  1824,  pp.  31-43. 

This  article  contains  the  first  attempt  at  a differentiation  of  the  “ alluvial  formation  ” 
of  the  Coastal  Plain.  The  Tertiary  is  recognized. 

Finch,  J.  Travels  in  the  United  States  of  America  and  Canada. 

London,  1833,  8vo,  355  pp. 

The  author  refers  to  the  geology  at  Fort  Washington. 

Fontaine,  W.  M.  Notes  on  the  ]\Iesozoic  strata  of  Virginia. 

Amer.  Jour.  Sci.,  3rd  series,  vol.  xvii,  1879,  pp.  25-39.  151-157,  229-239. 

The  relations  of  the  Eocene  to  Mesozoic  strata  are  indicated. 


MAEYLAXD  GEOLOGICAL  SURYEA" 


37 


The  artesian  well  at  Fort  Monroe,  Va. 

The  Virginias,  vol.  iii,  1882,  pp.  18-19. 

The  Tertiary  is  regarded  as  haying  a thickness  of  800  feet. 

Harris,  Gilbert  D.  Eepnhlication  of  ConracFs  Fossil  Shells  of  the 
Tertiary  Formations  of  North  America. 

Washington,  1893,  8vo,  pp.  1-121,  pis.  i-xx. 

The  repnblication  of  Conrad’s  important  monograph  on  Tertiary  Mollusca,  for  many 
years  out  of  print,  has  rendered  it  now  available  to  all  paleontologists. 

On  the  geological  position  of  the  Eocene  deposits  of  Mary- 
land and  Virginia. 

Ainer.  Jour.  Sci.,  3rd  series,  vol.  xlvii,  1894,  pp.  301-304. 

The  Eocene  deposits  of  the  Middle  Atlantic  Slope  are  correlated  by  the  author  with 
the  Bell’s  Landing  substage  of  the  Lignitie  of  the  Gulf. 

The  Lignitie  Stage. 

Bull.  Amer.  Pal.,  vol.  ii.  No.  9,  1897,  pp.  193-294  (1-102),  pis.  vii-xx  (i-xiv), 
and  vol.  iii.  No.  11,  1899,  pp.  1-22,  pis.  i-xii. 

Many  species  found  in  the  Maryland  Eocene  are  described  and  figured. 

Haa'den,  H.  H.  Geological  essay,  or  an  inquiry  into  some  of  the 
geological  phenomena  to  he  found  in  various  parts  of  America  and  else- 
where. 

Baltimore,  1820,  8vo,  viii,  412  pp. 

The  general  features  of  the  “ alluvial  formation  ” of  the  Coastal  Plain  are  desci-ibed 
in  this  volume. 

Heilprin,  a.  a comparison  of  the  Eocene  Mollusca  of  the  sonth- 
eastern  United  States  and  western  Europe  in  relation  to  the  determina- 
tion of  identical  forms. 

Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  xxxi,  1879,  pp.  217-225. 

Several  forms  known  to  occur  in  Maryland  and  Virginia  are  compared  in  this  article 
with  European  species. 

On  the  stratigraphical  evidence  afforded  by  the  Tertiary  fos- 
sils of  the  peninsula  of  Maryland. 

Ibid.,  vol.  xxxii,  1880,  pp.  20-33. 

The  author  calls  attention  to  the  few  Eocene  fossils  in  the  Maryland  strata,  and  the 
marked  difference  between  the  Eocene  and  Miocene  faunas. 

Note  on  the  approximate  position  of  the  Eocene  deposits  of 

Maryland. 

Ibid.,  vol.  xxxiii,  1881,  pp.  444-447. 

The  Maryland  Eocene  is  regarded  as  “ nearly  e<iual  to  that  of  the  Thanet  sands  of 
England  and  the  Bracheux  sand  of  the  Paris  Basin,  or  of  the  English  Bognor  rock 
(London  Clay).”  It  is  also  correlated  with  deposits  near  the  base  of  the  “ Buhrstone  ” 
or  possibly  even  the  “Eolignitic  ” of  the  Gulf. 


38 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


North  American  Tertiary  Ostreidae. 

4th  Ann.  Kept.  U.  S.  Geol.  Surv.,  1882-83,  Washing-ton,  1884,  pp.  309-316. 

(Appendix  I to  C.  x\.  White’s  Fossil  Ostreidae  of  North  America). 

Gives  Ostrea  compressirostra  Say  (309),  0.  eversa  (310). 

Contributions  to  the  Tertiary  geology  and  paleontology  of  the 

United  States. 

Philadelphia,  1884,  4to,  117  pp.  and  map. 

In  this  volume  the  author  gives  a full  discussion  of  the  Eocene  deposits  of  Delaware, 
Maryland  and  Virginia. 

The  Tertiary  Geology  of  the  Eastern  and  Southern  United 

States. 

Jour.  Acad.  Nat.  Sci.,  Phlla.,  2nd  ser.,  vol.  ix,  1884,  pp.  115-154,  map. 

A monographic  study  of  the  formations  and  a correlation  of  the  different  areas 
among  themselves  and  wuth  those  of  Europe.  Description  of  Eocene  and  Miocene  forma- 
tions of  Maryland. 

On  some  new  species  of  Eocene  Mollusca  from  the  southern 

United  States. 

U.  S.  Nat.  Mus.  Proc.,  vol.  iii,  1886,  pp.  149-152  and  plate. 

This  article  contains  a description  of  Crassatella  decUiHs. 

Explorations  on  the  West  Coast  of  Elorida. 

Trans.  Wagner  Free  Inst.  Sci.,  vol.  i,  1887. 

The  relation  of  the  Maryland  Eocene  to  that  of  New  Jersey,  Alabama,  Mississippi 
and  of  Europe  is  briefly  indicated  (p.  127). 

Heinrich,  0.  J.  The  Mesozoic  formation  in  Virginia. 

Trans.  Am.  Inst.  Min.  Engs.,  vol.  vi,  1878,  pp.  227-274. 

The  relations  of  the  Eocene  to  Mesozoic  strata  are  indicated. 

Higgins,  James.  Reports  of  the  State  agricultural  chemist  of  Mary- 
land for  1850,  1853,  1853,  1854,  1856,  and  1858. 

These  reports  contain  brief  references  to  the  Eocene  deposits,  chiefly  of  an  econ- 
omic character. 

Hotchkiss,  Jed.  Virginia:  a geographical  and  political  summary, 
embracing  a description  of  the  State,  its  geology,  soils,  minerals,  climate, 
etc. 

Eichmond,  1876,  8vo,  pp.  iv,  319,  and  4 maps. 

The  book  contains  a description  of  the  Eocene  deposits  of  Virginia,  based  largely  on 
the  earlier  observations  of  Rogers. 

Kalm,  Peter.  En  Eesa  til  Norra  America.  Stockholm,  1753-1761, 
8°,  3 vols.,  with  English,  German,  and  French  translations. 

This  work  contains  the  earliest  recorded  observations  on  the  geology  of  the  Coastal 
Plain. 


MARYLAND  CxEOLOGICAL  SURVEY 


39 


Lea,  Henry  C.  Catalogue  of  the  Tertiary  Testacea  of  the  United 
States. 

Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  1848,  pp.  95-107. 

The  author  includes  in  his  list  the  names  of  the  Eocene  fossils  from  the  IMiddle 
Atlantic  Slope. 

Lea,  Isaac.  Contributions  to  geology. 

Philadelphia,  1833,  8vo,  227  pp.  and  6 plates. 

The  Fort  Washington  deposits  are  correlated  by  the  author  with  those  of  Claiborne, 
Ala.,  and  a description  is  given  of  many  forms  from  the  latter  locality,  some  of  which 
have  since  been  found  in  Maryland. 

Lyell,  Charles.  On  the  Tertiary  formations  and  their  connection 
with  the  chalk  in  Virginia  and  other  parts  of  the  United  States. 

Proc.  Geol.  Soc.,  London,  vol.  iii,  1842,  pp.  735-742. 

The  article  contains  a description  of  the  Janies  River  Eocene  deposits,  and  the  im- 
portance of  Venericardia  planicosta  as  a type  fossil  is  discussed. 

On  the  Miocene  Tertiary  strata  of  Maryland,  Virginia,  and 

North  and  South  Carolina. 

Proc.  Geol.  Soc.,  London,  vol.  iv,  1845,  pp.  547-563;  Quart.  Jour.  Geol.  Soc., 
London,  vol.  i,  1845,  pp.  413-429. 

The  author  refers  to  the  Eocene  in  several  of  the  sections  that  are  given. 

Observations  on  the  white  limestone  and  other  Eocene  or 

older  Tertiary  formations  of  Virginia,  South  Carolina,  and  Georgia. 

Proc.  Geol.  Soc.,  London,  vol.  iv,  1845,  pp.  563-576;  Quart.  Jour.  Geol.  Soc., 
London,  vol.  i,  1845,  pp.  429-442. 

The  author  gives  a description  of  the  Eocene  deposits  of  the  James  River,  as  well 
as  of  the  Richmond  and  Petersburg  areas.  The  occurrence  of  Venericardia  planicosta 
and  of  a form  similar  to  Ostrea  bellovacina  of  Europe  is  mentioned. 

Maclure,  W.  Observations  on  the  geology  of  the  United  States,  ex- 
planatory of  a geological  map. 

Trans.  Amer.  Philos.  Soc.,  old  series,  vol.  vi,  1809,  pp.  411-428. 

Observations  on  the  geology  of  the  United  States  of  North 

America,  etc. 

Ibid.,  new  series,  vol.  i,  1817,  pp.  1-92. 

Observations  on  the  geology  of  the  United  States  of  America. 

Philadelphia,  1817,  8vo,  130  pp. 

In  the  publications  of  Maclure  the  entire  Coastal  Plain  is  referred  to  the  “ alluvial 
formation.”  A translation  of  the  first  article  above  mentioned  appeared  in  the  Journal 
de  Physique,  vol.  Ixix,  1809,  pp.  204-213,  and  vol.  Ixxii,  1811,  pp.  137-165,  and  of  the 
second  article  in  Leonard’s  Zeitschrift,  Band  I,  1826,  pp.  124-1.38. 

Maury,. M.  F.  Physical  survey  of  Virginia.  Richmond,  i,  1868,  8°, 
90  pp.;  ii,  1878,  8°,  14-2  pp. 

This  publication  contains  several  references  to  the  stratigraphical  relations  of  the 
Eocene. 


40 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


McGee,  ^Y  J Three  formations  of  the  Middle  Atlantic  Slope. 

Amer.  Jour.  Sci.,  3rd  ser.,  vol.  xxxv,  1888,  pp.  120-143,  328-330,  367-388,  448- 
466. 

The  author  discusses  the  general  features  of  Coastal  Plain  stratigraphy,  and  refers 
to  the  contact  of  the  Eocene  and  Potomac  in  Virginia. 

Map  of  the  United  States  exhibiting  the  present  status  of 

knowledge  relating  to  the  areal  distribution  of  geologic  groups. 

Fifth  Ann.  Eept.  U.  S.  Geol.  Survey,  1885,  pp.  36-38,  maij  as  pi.  ii. 

This  map,  compiled  from  various  sources,  sho-ws  on  a small  scale  the  distribution  of 
the  Eocene  deposits  in  the  Middle  Atlantic  Slope. 

The  Lafayette  formation. 

Twelfth  Ann.  Kept.  U.  S.  Geol.  Survey,  1892,  pp.  347-521,  pis.  xxxii-xli. 

The  Eocene  deposits  of  the  Middle  Atlantic  Slope  are  described  and  the  physical 
history  of  the  formation  is  pointed  out. 

Geology  of  Washington  and  Vicinity. 

Guide  to  Washington  and  its  Scientific  Institutions,  1891,  pp.  38-64;  and 
Congres  Geologique  International.  Compte  Eendu,  5me  Session,  Washington 
1891,  pp.  219-251,  1893. 

Article  prepared  with  the  collaboration  of  G.  H.  Williams,  N.  H.  Dart  on  and  Bailey 
Willis.  Contains  description  of  the  Eocene  by  Darton. 

Miller,  S.  A.  North  American  Mesozoic  and  Cenozoic  geology  and 
paleontology. 

Cincinnati,  1881,  8vo,  338  pp. 

Brief  general  statements  regarding  the  Eocene  deposits  of  the  Middle  Atlantic  Slope 
are  made  by  the  author. 

Morton,  S.  G.  Geological  observations  on  the  Secondary,  Tertiary, 
and  Alluvial  formations  of  the  Atlantic  Coast  of  the  United  States  of 
America.  Arranged  from  the  notes  of  Gardner  Vanuxem. 

Jour.  Acad.  Nat.  Sci.,  Phila.,  vol.  vi,  1829,  pp.  59-71. 

The  attempt  is  made  by  the  author,  in  a general  way,  to  delimit  more  accurately  the 
several  formations  of  the  Atlantic  Coastal  Plain,  although  at  that  time  the  Eocene  was 
not  differentiated. 

Synopsis  of  the  organic  remains  of  the  Cretaceous  group  of 

the  United  States.  x\ppendix:  Catalogue  of  the  fossil  shells  of  the 
Tertiary  formations  of  the  United  States. 

Philadelphia,  8vo,  1834,  88,  8 pp. 

(Abst.)  Amer.  Jour.  Sci.,  vol.  xvii,  1835,  pp.  377-381. 

The  author  gives  in  his  catalogue  the  Atlantic  Tertiary  species  which  had  been  up 
to  that  time  described. 

Additional  Observations  [to  Synopsis]. 

Philadelphia,  8vo,  1835,  4 pp. 

The  author  adds  Gryphaea  vomer  to  the  Eocene  forms  from  Upper  Marlboro  and 
Piscataway. 


MARYLAND  GEOLOGICAL  SURVEY 


41 


Murchison,  E.  I.  Secondary  and  Tertiary  rocks  and  superficial  de- 
posits of  North  America. 

Proc.  Geol.  Soc.,  London,  vol.  iv,  1843,  pp.  127-133. 

The  author  reyiews  the  results  of  Lyell’s  investigations  upon  the  Tertiary  strata  of 
America,  adding  his  own  interpretation  of  some  points. 

Nickles,  John  M.,  and  Bassler,  Eay  S.  A Synopsis  of  American 
Fossil  Bryozoa. 

Bull.  173,  U.  S.  Geol.  Survey,  1900,  p.  72. 

Upper  Marlboro  is  included  in  the  list  of  Eocene  localities. 

• Pierce,  J.  Practical  remarks  on  the  shell-marl  region  of  the  eastern 
parts  of  Virginia  and  Maryland,  and  upon  the  bituminous  coal  forma- 
tion in  Virginia  and  the  contiguous  region. 

Amer.  Jour.  Sci.,  vol.  ii,  1826,  pp.  54-59. 

Reference  is  made  to  the  localities  at  Upper  Marlboro,  and  Potomac  Creek. 

Eogers,  ay.  B.  On  the  discovery  of  greensand  in  the  calcareous  de- 
posits of  eastern  Virginia,  and  on  the  probable  existence  of  this  sub- 
stance in  extensive  beds  near  the  western  limits  of  our  ordinary  marl. 

Farmer’s  Reg'ister,  vol.  ii,  1834.  Reprinted  in  the  Geology  of  the  Virginias, 
1884,  pp.  3-9. 

The  author  refers  in  a general  way  to  the  greensand  deposits  of  eastern  Virginia, 
which  he  compares  with  similar  beds  in  New  Jersey. 

Further  observations  on  the  greensand  and  calcareous  marl  of 

Aurginia. 

Farmer’s  Register,  May,  1835.  Reprinted  in  Geology  of  the  Virginias, 
1884,  pp.  11-20. 

In  this  publication  the  author  makes  the  first  announcement  of  the  occurrence  of  the 
Eocene  in  Virginia. 

Eeport  of  the  geological  reconnoissance  of  the  State  of  Vir- 
ginia, made  under  the  appointment  of  the  Board  of  Public  AYorks,  1835. 
Eichmond,  1836,  4°,  52  pp.  and  plate. 

Reprinted,  Phila.,  1836,.  8vo,  143  pp.  and  plate,  and  in  Geology  of  the  Vir- 
ginias, 1884,  pp.  21-122. 

This  report  contains  a general  statement  regarding  the  “ Eocene  Marl  District  ” of 
eastern  Virginia,  with  a description  of  the  lithologic  character  of  the  strata  in  the 
different  river  valleys. 

Eeport  of  the  progress  of  the  geological  survey  of  the  State 

of  YTrginia  for  1836.  Eichmond,  1837,  4°,  14  pp. 

Reprinted,  Phila.,  1838,  8vo,  and  in  Geology  of  the  Virginias,  1884,  pp.  123- 

145. 

The  Eocene  deposits  of  the  peninsula  between  the  Potomac  and  Rappahannock  rivers 
are  described  by  the  author. 


42 


THE  EOCENE  DEPOSITS  OF  MAKYLAND 


Eeport  of  the  progress  of  the  geological  survey  of  the  State 

of  Virginia  for  1837.  Kichmond,  1838,  4°,  24  pp. 

Eeprinted,  Phila,,  1838,  8vo,  and  in  Geolog-y  of  the  Virginias,  1884,  pp.  147- 
188. 

Brief  mention  is  made  of  the  Eocene  deposits  on  the  James  Biver. 

Eeport  of  the  progress  of  the  geological  survey  of  the  State 

of  Virginia  for  1839.  Eichmond,  1840,  8°,  161  pp. 

Eeprinted  in  Geology  of  the  Virginias,  1884,  pp.  245-410. 

In  this  report  the  author  describes  in  much  detail  the  “ Tertiary  Marl  region  south 
of  the  James  River.” 

Eeport  of  the  progress  of  the  geological  survey  of  the  State 

of  Virginia  for  1840.  Eichmond,  1841,  8°,  132  pp. 

Eeprinted  in  Geology  of  the  Virginias,  1884,  pp.  411-535. 

This  report  contains  a description  of  the  “ Tertiary  Marl  region  between  the  Potomac 
and  the  Rappahannock  rivers,”  and  also  of  the  ” Tertiary  beds  in  the  vicinity  of 
Richmond.” 

— Infusorial  deposit  of  Virginia  in  the  Fort  Monroe  artesian 

well. 

The  Virginias,  vol.  iii,  1882,  pp.  151-152.  Eeprinted  in  Geology  of  the 
Virginias,  1884,  pp.  733-736. 

The  character  of  the  Eocene  strata  penetrated  in  the  well-boring  is  given  at  various 
depths. 

Eogers,  W.  B.  and  H.  D.  Contributions  to  the  geology  of  the  Ter- 
tiary formations  of  Virginia. 

Trans.  Amer.  Philos.  Soc.,  new  series,  vol.  v,  1837,  pp.  319-341;  vol.  vi,  1839, 
pp.  347-370,  371-377,  pis.  26-30.  Eeprinted  in  Geology  of  the  Virginias,  1884, 
pp.  659-673,  pis.  i-v. 

The  authors  describe  Nucula  cult  elli for  mis,  N.  parva,  and  Cytherea  ovata  from 
Coggins  Point,  James  River,  Ostrea  sinuosa  from  Evergreen,  James  River,  Cucullaea 
transversa  and  Venericardia  ascia  from  King  George  County,  Cucullaea  ondchela  and 
Crassatella  capri-cranium,  from  the  peninsula  between  the  Potomac  and  Rappahannock 
rivers,  and  Cytherea  lenticularis  from  “eastern  Virginia.” 

The  same  [abstract]. 

Proc.  Amer.  Philos.  Soc.,  vol.  i,  1839,  pp.  88-90. 

Euffin,  Edmund.  Description  of  a nut  found  in  Eocene  marl. 

Amer.  Jour.  Sci.,  2nd  series,  vol.  ix,  1850,  pp.  127-129. 

The  author  describes  a nut  found  in  the  Eocene  marl  of  the  Pamunkey  River,  Virginia. 

Say,  Thomas.  An  account  of  some  of  the  fossil  shells  of  Maryland. 

Jour.  Acad.  Nat.  Sci.,  Philadelphia,  vol.  iv,  1828,  pp.  124-155,  pis.  7-13. 

In  this  article  Ostrea  compressirostra  is  described,  but  no  locality  is  given. 

ScHOPF,  J.  D.  Beytrage  zur  mineralogischen  Kenntniss  des  ostlichen 
Theils  von  Nordamerica  und  seiner  Gebtirge.  Erlanger,  8°,  1787, 
194  pp. 

The  author  gives  the  result  of  his  observations  in  the  eastern  United  States,  referring 
to  some  of  the  more  striking  features  of  the  Atlantic  Coastal  Plain. 


MAEYLAXD  GEOLOGICAL  SURVEY 


43 


Tuomey',  M.  Discovery  of  a chambered  univalve  fossil  in  the  Eo- 
cene Tertiary  of  James  Eiver,  Virginia. 

Amer.  Jonr.  Sci.,  vol.  xliii,  1842,  187. 

This  article  contains  some  conclusions  of  the  author  regarding  the  stratigraphy  of  the 
Eocene,  based  on  a section  exposed  in  a shaft  sunk  at  Evergreen  on  the  James  River. 

Tysox,  Philip  T.  First  report  of  Philip  T.  Tyson,  State  agricul- 
tural chemist,  to  the  House  of  Delegates  of  Maryland,  January,  1860. 

Annapolis,  1860,  8vo,  xi,  145,  and  20  pp.  and  one  map. 

The  author  describes  the  Tertiary  formations  collectively,  stating  that  the  work  has 
not  progressed  far  enough  to  separate  the  different  divisions,  although  he  refers  to  the 
Eocene  greensand  marl. 

New  topographical  atlas  of  the  State  of  Maryland,  etc.  1873. 

This  work  contains  a general  statement  regarding  the  geology  of  Maryland,  including 
a description  of  the  Eocene. 

Uhler,  P.  P.  Observations  on  the  Eocene  Tertiary  and  its  Creta- 
ceous associates  in  the  State  of  Maryland. 

Trans.  Maryland  Acad.  Sci.,  vol.  i,  1888,  pp.  10-32. 

Additions  to  observations  on  the  Cretaceous  and  Eocene  for- 
mations of  Maryland. 

Trans.  Maryland  Acad.  Sci.,  vol.  i,  1889-1890,  pp.  45-72. 

Notes  and  illustrations  to  Observations  on  the  Cretaceous 

and  Eocene  formations  of  Maryland.^’ 

Trans.  Maryland  Acad.  Sci.,  vol.  i,  1890,  f)p.  97-104. 

The  above  articles  contain  an  extensive  description  of  the  Eocene  and  a discussion 
of  its  relations  to  the  Cretaceous. 

Vax  Kexsselaer,  J.  Lectures  on  geology.  New  York,  8°,  1825, 
350  pp. 

The  author  accepts  the  conclusions  of  Finch  regarding  the  so-called  Alluvial  forma- 
tion,” and  describes  briefly  the  Tertiary  foi’mations  of  the  Xorthern  Atlantic  Coastal 
Plain. 

Vaughax,  T.  AVay'laxd.  Contributions  to  the  Eocene  Fauna  of  the 
Middle  Atlantic  Slope.  Coelenterata. 

Johns  Hopkins  Univ.  Circ.,  1895,  vol.  xv,  p.  6. 

The  author  describes  Paracyathus  (?)  clarkeanus  and  Turhinolia  acuticostata  from 
Potomac  Creek. 

The  Eocene  Deposits  in  the  Middle  Atlantic  Slope  in  Dela- 
ware, Maryland  and  Virginia.  Coelenterata. 

Bull.  141,  U.  S.  Geol.  Survey,  1896,  j^p.  89-91. 

The  same  forms  are  described  as  in  the  above  article. 

Eocene  and  Lower  Oligocene  Corals  of  the  United  States. 

Monog-raph  U.  S.  Geol.  Survey,  No.  xxxix,  Washington,  1900. 

The  author  describes  in  much  detail  the  coral  species  from  Maryland  and  Virginia. 


44 


THE  EOCEXE  DEPOSITS  OF  MAEYLAND 


General  Stratigraphic  Eelatioxs. 

Our  knowledge  of  the  Tertiary  geology  and  paleontology  of  the  Middle 
Atlantic  Slope  has  been  largely  increased  since  the  days  of  Conrad  and 
Eogers,  yet  few  fields  have  afforded  better  opportunities  in  recent  years 
for  continued  investigatioip  since  very  divergent  opinions  have  prevailed 
and  even  to-day  find  expression  in  the  different  interpretations  of  the 
data. 

Both  the  Eocene  and  the  Xeocene  divisions  of  the  Tertiary  in  this 
area  have  broad  surface  exposures,  and  are  represented  by  character- 
istic sections  along  the  leading  waterways.  Both  are  also  highly  fossilif- 
erous,  although  the  ^^eocene  shows  a greater  diversity  of  species  than 
does  the  Eocene.  This  difference,  however,  is  not  so  great  as  one  would 
infer  from  a perusal  of  the  literature,  since  a large  number  of  Eocene 
species,  many  of  them  very  common,  have  been  until  recently  unrecog- 
nized, or  at  least  unrecorded. 

A brief  discussion  of  the  general  relations  of  the  Coastal  Plain  de- 
posits in  the  Middle  Atlantic  Slope  is  essential  to  a clear  comprehen- 
sion of  the  Eocene  formations.,  A more  detailed  history  of  the  several 
groups  of  deposits  will  be  found  in  other  volumes  of  the  Survey. 

The  Coastal  Plain  consists  geologically  of  a series  of  formations  that 
were  deposited  as  moderately  thin  sheets,  one  above  another,  along  the 
eastern  border  of  the  crystalline  belt,  elsewhere  referred  to  as  the  Pied- 
mont Plateau.  The  coastal  deposits  are  slightly  inclined  eastward,  so 
that  successively  later  members  of  the  series  are  encountered  in  passing 
from  the  interior  of  the  country  toward  the  coast. 

From  the  beginning  of  deposition  in  the  coastal  region  until  the  pres- 
ent time  sedimentation  has  apparently  been  constantly  in  progress  over 
some  portions  of  the  area.  Differential  movements  of  the  sea-floor,  with 
its  accumulated  sediments,  took  place,  however,  from  time  to  time,  so 
that  the  formations  present  much  complexity  along  their  western  mar- 
gins. It  is  not  uncommon  there  to  find  certain  members  of  the  series 
lacking,  as  renewed  deposition  carried  a later  formation  beyond  its  pre- 
decessors. In  the  absence  of  distinctive  fossils,  the  discrimination  of 
the  different  horizons  at  such  points  is  often  attended  with  great  un- 
certainty. 


MARYLAND  GEOLOGICAL  SURVEY, 


EOCENE,  PLATE  II. 


Fig.  l.-FARM-  AND  WOOD-LAND  ALONG  SOUTH  RIVER. 


Fig.  2.- farm-land  NEAR  ANNAPOLIS  WATER  WORKS. 
VIEWS  OF  SURFACE  OF  EOCENE  COUNTRY. 


V 


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]\rAKYLAXD  GEOLOGICAL  SUKVEY 


45 


Deformation  has  also  affected  the  region  to  a limited  extent,  the 
strata  being  slightly  warped,  so  that  the  plane  of  bedding  does  not  main- 
tain a uniform  strike  and  dip.  This  is  particularly  marked  along  the 
western  border  of  the  area.  There  have  also  been  slight  displacements 
in  various  localities.  McGee ' has  described  one  of  these,  while  others 
have  been  observed  by  the  junior  author  of  this  report. 

It  seems  highly  probable  that  every  geological  period  from  the  Creta- 
ceous (possibly  Upper  Jurassic)  to  the  Pleistocene  is  represented,  al- 
though in  one  or  two  instances  the  lack  of  characteristic  fossils  renders 
the  taxonomic  position  of  certain  formations  difficult  of  absolute  deter- 
mination. 

CRETACEOUS. 

The  Cretaceous  (in  part  possibly  Upper  Jurassic)  is  extensively  repre- 
sented in  the  Middle  Atlantic  Slope.  The  deposits  of  this  period  con- 
sist of  a series  of  basal  formations  that  has  been  designated  the  Potomac 
group,  comprising  the  Patuxent,  Arundel,  Patapsco  and  Earitan  forma- 
tions, none  of  which  was  deposited  under  marine  conditions,  overlain  in 
succession  by  the  Matawan,  Monmouth,  and  Eancocas  formations,  which 
are  distinctly  marine  in  origin.  All  but  the  Potomac  formations  gradu- 
ally disappear  southward,  that  group  alone  of  the  Cretaceous  deposits 
being  recognized  in  Virginia.  Unconformities  characterize  the  several 
members  of  the  Potomac  group  while  the  marine  deposits  are  also  un- 
conformable  to  the  older  strata. 

The  Potomac  group  consists  chiefly  of  sands  and  clays,  the  former 
frequently  arkosic,  with  gravel  at  certain  points  where  the  shore  accu- 
mulations are  still  preserved.  The  deposits  of  the  Patuxent  formation 
are  highly  arkosic,  the  sands  and  clays  showing  both  a vertical  and  a 
horizontal  gradation  into  one  another.  The  sand  layers  are  seldom 
widely  extended,  being  generally  lenticular  masses,  which  rapidly  dimin- 
ish in  thickness  from  their  centers.  Dark  colored  clays  abound  in  the 
Arundel  formation  and  have  yielded  large  amounts  of  nodular  carbonate 
of  iron.  Highly  colored  and  variegated  clays  largely  make  up  the 
Patapsco  formation.  Thick-bedded  and  widely  extended  white  sands 


1 7th  Ann.  Kept.,  U.  S.  Geol.  Survey,  pp.  616-633. 


46 


THE  EOCENE  DEPOSITS  OF  MAKYLAND 


with  interstratified  clays  characterize  the  Earitan  formation.  The  fos- 
sils consist  chiefly  of  the  hones  of  dinosanrian  reptiles  and  of  leaf  im- 
pressions, the  former  confined  to  the  Arundel  formation,  the  latter  pre- 
dominating in  the  Patapsco  and  Earitan  formations.  The  plants  show 
beyond  a doubt  the  Cretaceous  age  of  the  two  upper  formations  while 
the  reptiles  have  been  regarded  by  high  authority  to  he  upper  Jurassic. 

The  Matawan  formation  is  formed  largely  of  fine  sands  and  clays, 
clearly  stratified,  and  in  the  case  of  the  clays  often  laminated.  The 
clays  and  sandy  days  are  generally  dark,  often  black,  in  color.  They 
are  commonly  micaceous,  and  at  time  sparingly  glauconitic.  The  very 
homogeneous  and  persistent  character  of  the  beds  is  in  marked  contrast 
to  the  deposits  of  the  Potomac  group  which  they  overlie.  The  fossils 
consist  largely  of  marine  Mollusca  which  indicate  the  upper  Cretaceous 
age  of  the  deposits. 

The  Monmouth  formation  consists  chiefly  of  greensand  deposits, 
although  the  glauconitic  element  is  not  so  pronounced  or  so  persistent 
south  of  the  Chesapeake  as  in  the  more  northern  districts.  The  strata 
are  more  arenaceous,  and  as  a result  the  materials  weather  more  readily, 
showing  generally  in  greater  or  less  degree  the  characteristic  reddish 
color  of  the  hydrated  peroxide  of  iron.  The  common  and  characteristic 
Gryphaea  vesicularis,  Exogyra  costata,  and  Belemnitella  americana  are 
widely  found,  with  other  typical  forms. 

The  Eancocas  formation  is  also  largely  composed  of  greensands,  gen- 
erally more  glauconitic  than  the  Monmouth  formation,  although  at 
times  somewhat  argillaceous.  The  strata  are  much  weathered  where 
exposed,  and  often  appear  as  a firm  red  rock,  the  grains  being  cemented 
by  the  iron  oxide.  The  deposits  have  afforded  Terebratula  liarlani, 
Gryphaea  hryani,  and  other  characteristic  species  of  the  New  Jersey  area. 

EOCENE. 

The  Eocene  is  represented  in  the  Middle  Atlantic  Slope  by  a group  of 
deposits  stretching  along  the  eastern  margin  of  the  Coastal  Plain  and 
overlying  the  Cretaceous  formations  unconform  ably.  They  will  he 
described  in  much  detail  in  the  following  pages. 

The  deposits  consist  largely  of  greensand  marls,  which  may,  how- 


MARYLAND  GEOLOGICAL  SURVEIT 


47 


ever,  by  weathering,  lose  their  characteristic  green  color,  and  by  the 
deposition  of  a greater  or  less  amount  of  hydrous  iron  oxide  become 
firm  red  or  brown  sandstones  or  incoherent  red  sands.  At  times,  notably 
in  Southern  Maryland  and  Virginia,  the  strata  become  highly  argilla- 
ceous, the  glauconitic  elements  largely  or  quite  disappearing.  Infre- 
quently coarse  sands  and  even  gravels  are  found,  the  latter  chiefly  toward 
the  base  of  the  formation  and  near  the  ancient  shore  line,  especially 
toward  the  northeast  in  central  and  eastern  Maryland. 

Very  commonly  the  shells  of  organisms  are  so  numerous  as  to  form 
the  chief  constituent  of  certain  beds.  Notwithstanding  these  facts,  the 
deposits  are  remarkably  homogeneous,  although  recent  investigations 
have  shown  the  possibility  of  dividing  the  deposits  into  two  well-marked 
formations  on  both  lithologic  and  faunal  grounds.  The  lower  or  Aquia 
formation  is  much  more  highly  arenaceous  than  the  upper  or  Nanje- 
moy  formation  which,  particularly  in  its  lower  part,  is  generally  highly 
argillaceous.  The  Aquia  formation  is  also  much  more  calcareous  than 
the  Nanjemoy  formation,  indurated  layers  frequently  appearing  in  the 
former. 

NEOCENE. 

The  Neocene  deposits  occupy  the  region  to  the  southeast  of  and  over- 
lie  the  Eocene.  The  lower  beds  comprise  the  Chesapeake  group,  so 
named  from  the  superb  sections  found  exposed  on  the  shores  of  Chesa- 
peake Bay,  and  recognized  to  consist  of  three  well-defined  formations; 
the  upper  beds  comprise  the  Lafayette  formation.  The  Neocene  de- 
posits lie  unconformably  upon  those  of  the  Eocene  and  overlap  them 
along  their  western  border,  where  they  ultimately  come  to  rest  upon 
the  Cretaceous  toward  the  northeast.  They  are  in  turn  unconformably 
overlain  by  the  Pleistocene  deposits. 

The  Chesapeake  group  consists  of  sands,  cla)^s,  marls,  and  diatomace- 
ous  beds.  The  latter,  composed  almost  exclusively  of  the  tests  of  dia- 
toms, are  chiefly  confined  to  the  lower  portion  of  the  basal  formation, 
where  they  afford  striking,  light-colored  bluffs  along  many  of  the  larger 
stream  channels.  The  nearly  pure  diatomaceous  earth  reaches  a thick- 
ness of  30  or  40  feet,  although  the  remains  of  diatoms  are  found  scat- 
tered in  greater  or  less  amounts  throughout  much  of  the  overlying  strata. 


48 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


The  greater  portion  of  the  Chesapeake,  however,  is  composed  of  variously 
colored  sands  and  clays,  with  which  are  frequently  mingled  vast  numbers 
of  mollnscan  shells.  Sometimes  the  shelly  materials  form  so  large  a 
proportion  of  the  deposits  as  to  produce  nearly  pure  calcareous  strata, 
which  in  a partially  comminuted  state  may  become  cemented  into  hard 
limestone  ledges.  The  organic  remains  are  very  numerous  and  show 
the  Neocene  age  of  the  deposits.  Their  great  number  early  attracted 
the  attention  of  geologists,  in  whose  writings  descriptions  of  them  are 
frequently  found.  Several  faunas  have  been  distinguished  on  the  basis 
of  which,  as  well  as  on  stratigraphic  and  structural  grounds,  a number  of 
well-defined  formations  have  been  recognized  by  the  State  Geological 
Survey. 

Covering  the  Chesapeake  deposits  in  places,  is  a formation  composed 
of  gravel,  sand,  and  clay,  which  thus  far  has  afforded  no  distinctive 
fossils  upon  which  to  base  a determination  of  its  geologic  age.  From 
the  fact  that  the  deposits  rest  unconformably  upon  the  underlying 
Chesapeake,  and  are  in  turn  unconformably  overlain  by  the  Pleistocene, 
they  have  been  thought  to  represent  the  late  Neocene  or  Pliocene. 
The  apparent  similarity  of  these  deposits  to  those  in  Mississippi,  des- 
cribed by  Hilgard  under  the  name  of  the  Lafayette  formation,  has  led 
to  the  adoption  of  the  same  name  for  the  strata  of  the  Atlantic  Coast. 
The  beds  of  the  Lafayette  are  very  irregularly  stratified,  and  often 
change  rapidl}^  within  narrow  limits.  Toward  the  ancient  shore-line  the 
deposits  are  of  coarse  gravel,  through  which  is  scattered  a light-colored 
sandy  loam,  the  whole  cemented  at  times  by  hydrous  iron  oxide  into  a 
more  or  less  compact  conglomerate.  The  eastward  extension  of  the 
formation  shows  a gradual  lessening  of  the  coarser  elements  and  a larger 
admixture  of  loam.  Arkosic  materials  are  also  present  throughout  the 
formation,  while  the  coloring  and  manner  of  weathering  are  highly 
characteristic,  the  exposed  surfaces  presenting  what  is  known  as  case- 
hardening. 

PLEISTOCENE. 

Superficially  overlying  the  deposits  hitherto  described,  and  with 
marked  variations  in  thickness,  composition,  and  structure,  is  the  Pleis- 
tocene, which  lies  at  various  elevations  from  near  sea-level  to  200  feet 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  III. 


Fig.  1.— zones  2 to  6 at  mouth  of  AQUIA  creek. 


Fig.  2.-I5LOCKS  OF  ZONE  9,  LARGELY  COMPOSED  OF  TVRRITELLA  MORTONI. 


VIEWS  OF  EOCENE  SECTIONS. 


MARYLAND  GEOLOGICAL  SERVE  A' 


49 


in  the  dilterent  portions  of  the  region.  From  its  typical  development 
in  the  District  of  C^olnmbia  all  the  Pleistocene  deposits  of  the  Middle 
Atlantic  Slope  received  the  name  of  Cohunl)ia  formation  by  McGee  who 
described  three  distinct  phases,  viz.,  the  fluvial,  the  interfluvial,  and  the 
low-level.  Later  Darton  recognized  high-level  and  low-level  phases 
which  he  called  earlier  and  later  Columbia.  More  recently  Shattnck, 
of  the  State  Geological  Survey,  has  shown  that  greater  complexity  ex- 
ists in  the  Maryland  Pleistocene  deposits  than  had  been  before  recog- 
nized, and  that  the  later  Columbia  will  have  to  be  further  divided,  at 
least  locally.  The  Pleistocene  deposits  consist  of  gravel,  sand,  clay  and 
loam,  the  materials  in  general  becoming  finer  and  more  fully  stratified 
with  distance  from  the  old  shore-line  and  river-channels.  In  the  latter 
instance  they  at  times  contain  large  numbers  of  marine  mollnscan  shells, 
forming  a characteristic  calcareous  marl.  In  general,  however,  the  or- 
ganic remains  consist  largely  of  the  branches  and  leaves  of  terrestrial 
plants,  many  of  which  are  exquisitely  preserved. 

Distribution  of  the  Strata. 

The  Eocene  strata  of  the  Middle  Atlantic  Slope  form  a belt  of  varying 
width,  extending  from  northeast  to  southwest,  somewhat  to  the  west  of 
the  center  of  the  Coastal  Plain.  This  belt  has  been  traced  almost  con- 
tinuously from  the  southern  portion  of  Newcastle  county,  Delaware,  to 
the  valley  of  the  Nottoway  river,  in  southern  Virginia.  Although  at 
times  buried  beneath  later  deposits,  the  Eocene  presents  fine  exposures 
along  all  the  leading  stream-channels,  while  not  infrequently  broad 
outcrops  of  the  formation  appear  at  the  surface  in  the  intervening 
country. 

DELAWARE. 

In  Delaware  the  Eocene  is  found  apparently  only  near  the  Maryland 
line  and  slightly  to  the  south  of  the  central  portion  of  Newcastle  county, 
where  it  occupies  a restricted  portion  of  the  country  between  Appoquini- 
mink  Creek  on  the  north  and  Old  Duck  Creek  on  the  south.  Toward 
Delaware  Bay  the  formation  entirely  disappears,  the  Neocene  resting 
directly  upon  the  Cretaceous.  Even  in  the  limited  area  where  found 
4 


50 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


the  Neocene  deposits  widely  cover  the  Eocene,  so  that  in  the  absence  of 
large  streams  satisfactory  exposures  of  the  strata  are  not  found. 

MARYLAND. 

In  eastern  Maryland  the  conditions  of  outcrop  become  more  favorable, 
although  the  Neocene  deposits  still  cover  the  higher  portions  of  the 
country  while  the  Pleistocene  beds  often  till  the  valleys  and  cover  the 
lowlands  adjacent  to  the  Bay.  Several  tine  sections  are  found  in  the 
drainage  basin  of  the  Chester  river  in  both  Kent  and  Queen  Anne’s 
counties,  the  width  of  outcropping  beds  broadening  from  a few  miles  at 
the  boundary  to  more  than  10  miles  in  some  places,  and  reaching  quite 
to  the  valley  of  the  Sassafras 'river.  On  the  western  side  of  the  Chesa- 
peake the  Eocene  is  much  more  extensively  developed  than  upon  the 
eastern,  and  covers  wide  areas  in  Anne  Arundel,  Prince  George’s,  and 
Charles  counties. 

In  Anne  Arundel  county  the  best  sections  are  found  along  the  Severn 
and  South  rivers  and  their  tributaries.  The  highland  forming  the 
neck  below  the  lower  Magothy  and  Severn  rivers  is  largely  composed  of 
Eocene  beds,  the  most  western  exposure  being  found  at  Mount  Misery, 
near  Pound  Bay,  Severn  river,  at  an  altitude  of  100  feet,  while  eastward 
it  reaches  to  water-level.  P^he  higher  portions  of  the  area  between  the 
Severn  and  South  rivers  are  also  largely  made  up  of  Eocene  deposits,  as 
is  also  the  land  to  the  southwest  of  the  latter  stream  and  between  it  and 
the  valley  of  the  Patuxent  river.  Throughout  the  southern  portion  of 
the  county  the  Eocene  is,  however,  capped  by  the  Neocene  and  Pleisto- 
cene formations  along  the  central  highland. 

Much  of  the  western-central  portion  of  Prince  George’s  count}"  is  com- 
posed of  Eocene  strata,  many  fine  sections  occurring  along  the  western 
branches  of  the  Patuxent  river.  Along  the  Potomac  the  strata  are 
found  in  numerous  bold  bluffs,  while  broad  exposures  appear  in  the 
valleys  of  many  of  the  larger  tributaries,  notably  in  Piscataway  and  Mat- 
tawoman  creeks.  Upper  Marlboro,  on  the  eastern  side,  and  Fort  Wash- 
ington on  the  western  side  of  the  county  are  among  the  best  known 
localities  for  Eocene  fossils  in  the  Middle  Atlantic  Slope. 

In  Charles  county  the  Eocene  is  confined  to  its  western  half,  fine  sec- 


3IAKYLAXD  GEOLOGICAL  SUEVEY 


51 


tions  being  found  at  Clifton  Beach,  along  Port  Tobacco  Kiver,  and  at 
Popes  Creek.  Since  the  deposits  are  in  general  at  lower  levels  than  in 
Prince  George’s  county,  on  account  of  the  easterly  dip  of  the  beds,  the 
surface  outcrops  are  largely  covered  by  the  Neocene  and  Pleistocene 
formations. 

VIKGINIA. 

The  most  complete  section  of  the  Eocene  in  the  whole  Middle  Atlantic 
Slope  is  afforded  by  the  series  of  high  bluffs  on  the  western  bank  of  the 
Potomac  river  between  Aqnia  Creek  and  Mathias  Point,  in  eastern  Staf- 
ford and  northern  King  George  counties.  The  peninsula  .between  the 
Potomac  and  Eappahannock  rivers  is  to  a large  extent  formed  of  the 
Eocene  greensands,  which  also  appear  in  places  along  the  banks  of  the 
latter  stream,  outcropping  beneath  the  Columbia  formations.  The 
higher  levels  of  the  intervening  country  are  generally  capped  by  the 
Neocene  formations. 

Southward  the  Eocene  deposits  are  continued  in  eastern  Spottsyl- 
vania  and  in  Caroline  counties.  Eine  bluffs  of  the  characteristic  marls 
appear  on  the  south  bank  of  the  Rappahannock  at  several  points  above 
Port  Royal,  but  in  the  valley  of  the  Mattapony  they  are  much  less  prom- 
inent, although  occurring  at  frequent  intervals.  An  extensive  cover  of 
Neocene  deposits  occupies  the  higher  portions  of  the  country. 

In  the  valley  of  Pamunkey  river  and  its  tributaries,  particularly  in 
Hanover  county,  important  outcrops  of  the  Eocene  are  found.  Many 
of  the  fossils  described  by  Conrad  and  Rogers  were  obtained  from  this 
area. 

Farther  south,  in  the  valley  of  the  James  river,  are  many  of  the  most 
notable  occurrences  of  the  Eocene  in  the  whole  region.  At  Richmond, 
City  Point,  Evergreen,  and  Tar  Bay  prominent  exposures  are  found, 
the  two  latter  localities  particularly  being  rich  in  organic  remains.  At 
Petersburg  and  vicinity  the  Eocene  is  exposed  in  the  valley  of  the  Appo- 
mattox, but  the  sections  are  in  the  main  poor.  South  of  Petersburg  the 
only  exposure  so  far  as  known  is  at  Bolling’s  Bridge,  on  the  Nottoway 


river. 


52 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


General  Character  of  the  Deposits. 

COMPOSITION. 

The  Eocene  deposits  of  the  Middle  Atlantic  Slope  are  typically  glau- 
conitic, and  are  found  in  their  nnweathered  state  either  as  dark  gray  or 
green  sands  or  clays.  The  glauconite  varies  in  amount  from  very  nearly 
pure  beds  of  that  substance  to  deposits  in  which  the  arenaceous  and 
argillaceous  elements  predominate,  although  the  strata  are  generally 
very  homogeneous  through  considerable  thicknesses.  At  certain  hori- 
zons the  shells  of  organisms  are  found  commingled  with  the  glauconitic 
materials  in  such  numbers  as  largely  to  make  up  the  beds,  producing 
what  is  known  as  a greensand  marl.  These  beds  are  at  times  so  indu- 
rated as  to  form  true  limestone  ledges.  This  latter  phase  is  seen  t}qii- 
cally  developed  both  at  Fort  Washington  and  xVquia  Creek,  interstrati- 
fied  with  the  unconsolidated  greensand  layers. 

When  the  glauconite  is  weathered  the  deposits  lose  their  character- 
istic gray  or  green  color  and  generally  become  lighter  gray  with  reddish 
or  reddish-brown  streaks  or  bands,  or  may  be  entirely  of  the  latter  color. 
This  change  to  red  beds  particularly  characterizes  the  Eocene  deposits 
of  the  northern  portion  of  the  area,  from  the  • Patuxent  valley  to  the 
Xtelaware  line.  Throughout  much  of  this  territory  the  beds  are  coarse 
sands  and  become  predominently  so  toward  the  northeast.  This  t}^pe  of 
material  is  well  seen  on  Mount  Misery  on  the  north  bank  of  the  Severn 
river  and  at  various  points  on  the  Chester  river,  where  it  is  often  ce- 
mented into  a ferruginous  sandstone.  In  the  less  completely  weathered 
portions  of  the  formation  farther  south  the  change  is  indicated  by  the 
mottled  yellow  and  brown  appearance  of  the  more  superficial  beds,  many 
of  the  glauconitic  grains  still  showing  their  green  color  when  crushed. 
Thin  iron  crusts  at  times  appear  in  strata  of  this  character. 

It  is  noteworthy  that  in  the  northern  portion  of  the  area  the  cement- 
ing medium  of  the  indurated  beds  is  either  ferruginous  or  siliceous 
Avhile  in  the  southern  portion  it  is  chiefiy  calcareous. 

When  the  glauconite  is  largely  or,  more. rarely,  entirely  absent  in  the 
original  materials,  the  deposits  consist  of  black  or  gray  sands  or  cla}^s, 
the  latter  at  times  micaceous,  and  in  a few  instances  carbonaceous. 

A microscopical  examination  of  several  selected  specimens  from  dif- 


MARYLAND  GEOLOGICAL  SURVEY" 


53 


ferent  portions  of  the  area  shows  that  the  land-derived  elements  of  the 
deposits  are  mainly  quartzose,  quartz  grains  predominating.  Fragments 
of  crystalline  rocks  occur,  while  numerous  constituent  and  accessory 
minerals  derived  from  them  are  found. 

Chemical  analyses  of  several  typical  specimens,  made  by  Mr.  Peter 
Fireman,  of  Columbian  University,  give  the  following  results: 

ANALYSES  OF  MARLS. 


Nanjemoy. 

Aquia. 

I. 

II. 

III. 

Woodstock. 

Aquia  Creek. 

Winchester. 

Si02 

60.87 

31.58 

49.08 

AI2O3  -h  F6203  a 

32.68 

7.70 

41 . 25 

MgO' 

2.77 

1.05 

.76 

CaO 

1.66 

36.78 

None. 

Na20 

.38 

.59 

.43 

K2O 

.77 

.37 

.39 

H2O  at  110°  

3.58 

0.76 

1.31 

CO2 

3.17 

39.79 

.55 

Volatile  at  red  heat  less  CO2. . 

3.84 

.21 

6.37 

P2O5 

None. 

.09 

. 13 

98.57 

98.93 

100. 16 

Siliceous  matter 

73.48 

25 . 36 

52.30 

a Considerable  Fe203  in  all  samples. 

STRIKE  AND  DIP. 

The  strike  of  the  Eocene  deposits  in  Delaware  and  Maryland  is  ap- 
proximately northeast  and  southwest,  while  in  Virginia  the  prevailing 
trend  is  more  nearly  north  and  south.  This  change  in  direction  of 
strike  takes  place  in  the  area  between  the  Patuxent  and  Pappahannock 
rivers,  chiefly  in  the  Potomac  basin. 

Careful  measurements  made  at  each  of  the  local  sections  show  the 
dip  of  the  strata  to  be  on  the  average  about  12^  feet  to  the  mile.  The 
Turritella  bed  (Zone  9),  which  has  an  elevation  of  62  feet  at  its  base  in 
the  Aquia  Creek  section,  has  descended  to  25  feet  in  the  Potomac  Creek 
section,  3 miles  distant,  while  the  indurated  layer  (Zone  5),  which  stands 
at  24  feet  at  the  western  end  of  the  Aquia  Creek  section,  has  passed 
below  tide  level  2 miles  to  the  southeastward.  Similar  measurements 
made  at  Woodstock  and  in  some  of  the  intervening  ravines  do  not  change 
the  average  estimate  of  the  dip  found  at  the  two  ])oints  first  mentioned. 


54 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


There  are  some  exceptions  to  this  general  average,  however,  and  a local 
dip  of  22  feet  per  mile  was  observed  above  Popes  Creek. 

THICKNESS. 

It  is  evident,  therefore,  that  on  this  basis  of  calculation  the  thickness 
of  the  Eocene  strata  in  this  area  must  exceed  200  feet,  although  it  will 
probably  fall  short  of  300  feet,  the  amount  claimed  by  Darton. 

The  results  obtained  from  a study  of  the  various  section-lines  and 
well-borings  show  that  the  average  thickness  of  the  deposits  is  some- 
what more  than  200  feet,  although  estimates  based  on  the  Potomac 
river  section,  as  well  as  on  well-borings  in  the  area  to  the  east  of  Fred- 
ericksburg, show  that  it  somewhat  exceeds  that  amount  in  this  portion 
of  the  Middle  Atlantic  Slope. 

The  extensive  covering  of  post-Eocene  deposits  in  many  portions  of 
the  region  renders  it  impossible  to  obtain  data  upon  which  an  estimate 
can  be  based,  and  the  results  of  further  well-boring  will  be  awaited  with 
interest.  From  the  facts  already  obtained  it  seems  probable  that  there 
is  a slight  thickening  of  the  beds  to  the  eastward  along  the  line  of  dip. 

Origin  of  the  Materials. 

As  regards  their  origin,  the  chief  constituents  of  the  Eocene  deposits 
of  the  Middle  Atlantic  Slope  may  be  grouped  under  three  heads,  viz.: 
First,  the  arenaceous  and  argillaceous  elements,  which  are  land-derived; 
second,  the  calcareous  elements,  which  are  of  organic  origin;  and  third, 
the  glauconitic  elements,  which  are  of  secondary  formation. 

The  arenaceous  and  argillaceous  materials  were  undoubtedly  orig- 
inally derived  from  the  crystalline  rocks  of  the  Piedmont  Plateau,  with 
an  indefinite  admixture  from  the  Paleozoic  formations  of  the  Appala- 
chian region. 

The  organic  remains,  which  consist  very  largely  of  the  shells  of  mol- 
lusks,  are  generally  so  slightly  worn  or  broken  as  to  justify  the  belief 
that  they  were  little  disturbed  prior  to  their  burial  by  the  sediments  in 
which  they  are  now  found  entombed.  They  have,  however,  lost  con- 
siderably by  solution  since  they  were  deposited,  the  calcareous  matter 
removed  serving  as  a cement  to  produce  the  limestone  layers  found  at 
several  horizons  in  the  southern  Maryland  and  northern  Virginia  area. 


MARYLAND  GEOLOGICAL  SURYEIT 


55 


The  glauconitic  elements  are  secondary  in  character  and  were  formed 
ill  situ.  Since  they  enter  so  largely  into  the  formation  of  the  Eocene 
greensands,  their  character  and  origin  will  he  considered  somewhat  more 
fully. 

ORIGIN  OF  GREENSAND. 

Great  light  has  been  thrown  upon  this  subject  by  the  results  of  the 
deep-sea  dredgings  which  have  been  made  in  recent  years  by  the  vessels 
sent  out  on  scientific  expeditions  under  government  auspices.  The 
most  important  of  these  expeditions  was  that  of  the  Challenger,  sent  out 
by  the  British  Government  in  the  years  1872-76.  In  the  report  upon 
the  deep-sea  deposits,  based  upon  the  dredgings  of  that  expedition, 
Professors  Murray  and  Eenard,  the  authors,  present  the  results  of  their 
researches  as  to  the  character  and  distribution  of  greensand,  and  at  the 
same  time  propose  a theory  to  account  for  the  chemical  changes  which 
have  taken  place  to  produce  the  mineral  glauconite,  its  chief  constituent. 

The  glauconite  occurs  both  in  existing  seas  and  in  geological  deposits 
as  minute  grains,  seldom  exceeding  1 millimeter  in  diameter,  although 
these  grains  may  at  times  become  agglomerated  into  nodules  several 
centimeters  in  diameter  by  means  of  a phosphatic  cement.  The  grains 
are  always  more  or  less  rounded,  and  at  times  mammillated,  with  irregu- 
lar surface  outline.  They  are  generally  black  or  dark  green  in  color, 
but  become  brighter  green  upon  being  crushed.  The  surface  of  the 
grain  is  sometimes  covered  with  fine  punctures,  while  at  other  times  it 
is  smooth  and  shining.  Some  of  these  glauconite  grains  are  distinct 
internal  casts  of  foraminifera  and  of  other  calcareous  shells;  but  more 
often  they  are  only  indistinct  reproductions  of  the  form  of  the  chambers 
and  show  no  definite  connection  with  the  organisms  in  which  they  orig- 
inated. In  the  Eocene  deposits  the  foraminiferal  casts  are  less  distinctly 
seen  than  in  the  deposits  of  recent  seas,  yet  even  here  they  are  not  un- 
common. 

It  is  estimated  that  glauconitic  deposits  cover  approximately  1,000,000 
square  miles  of  the  sea  floor,  while  they  are  found  at  nearly  all  geolog- 
ical horizons  from  the  Cambrian  up.  On  the  present  ocean  floor  they 
are  limited  to  those  portions  adjacent  to  the  coasts,  and  for  the  most 
part  along  the  higher  parts  of  the  continental  slopes,  where  land- 


56 


THE  EOCEXE  DEPOSITS  OF  MARYLAND 


derived  materials  are  dejiosited  in  perceptible  yet  small  amounts.  The 
production  of  glauconite  seldom  reaches  to  greater  depths  than  900 
fathoms,  and  most  commonly  takes  place  between  100  and  200  fathoms. 
The  entrance  of  large  rivers  into  the  sea  or  the  prevalence  of  strong 
currents  bearing  sediment  tends  to  interfere  with  its  formation,  so  that 
its  area  of  distribution  is  seldom  continuous  for  great  distances. 

Although  glauconite  is  not  known  to  be  formed  except  in  the  pres- 
ence of  land-derived  materials,  its  production  is  accomplished  through 
the  intervention  of  foraminifera.  Their  connection  with  the  formation 
of  glauconite  was  first  shown  by  Ehrenberg^  in  1855,  as  the  result  of  a 
study  of  greensand  from  many  deposits  in  Europe  and  America.  Pro- 
fessor Bailey ""  in  the  succeeding  year  stated  that  the  formation  of  green- 
sand is  likewise  taking  place  on  the  floor  of  existing  seas  and  probably 
under  the  same  conditions  that  existed  in  past  geological  time. 

According  to  Murray  and  Eenard,  the  chambers  become  filled  with 
muddy  sediment,  and  if  we  admit  that  the  organic  matter  inclosed  in 
the  shell,  and  in  the  mud  itself,  transforms  the  iron  in  the  mud  into 
sulphide,  which  may  be  oxidized'  into  hydrate,  sulphur  being  at  the 
same  time  liberated,  this  sulphur  would  become  oxidized  into  sulphuric 
acid,  which  would  decompose  the  fine  clay,  setting  free  colloid  silica, 
alumina  being  removed  in  solution;  thus  we  have  colloid  silica  and  hy- 
drated oxide  of  iron  in  a state  most  suitable  for  their  combination.” 
The  potash  which  is  necessary  to  complete  the  composition  of  glauco- 
nite is  regarded  as  derived  from  the  decomposition  of  the  fragments  of 
crystalline  rocks  or  their  common  constituents,  orthoclase  and  white 
mica. 

Two  conditions,  then,  are  requisite  for  the  formation  of  glauconite: 
First,  the  deposition  of  mineral  particles  of  land-derived  origin;  and 
second,  the  presence  of  foraminifera.  In  the  absence  of  either,  glauco- 
nite will  not  be  produced.  On  the  other  hand,  it  is  retarded,  and  finally 
ceases  altogether,  as  the  amount  of  deposition  of  land-derived  materials 
increases  adjacent  to  the  coasts.  Only,  then,  within  circumscribed 
limits,  which  are  constantly  subject  to  modification,  is  the  formation  of 
glauconite  possible. 

1 Abhandl.  K.  Akad.  Wiss.  zu  Berlin,  185.5,  pp.  8.5-170. 

2 Proc.  Boston  Soc.  Nat.  Hist.,  vol.  v,  1856,  pp.  304-308. 


MARYLAND  GEOLOGICAL  SURVEY, 


EOCENE,  PLATE  IV. 


Fig.  l.-FORT  WASHINGTON  BLUFF,  BASAL  EOCENE  OVERLYING  CRETACEOUS. 


Fig.  2 -ZONES  2 TO  4 AT  I’.ASE  OF  AQUIA  CRICER  I’.LUFF. 


VIEWS  OF  EOCENE  SECTIONS. 


LIBRARV 

OF  THE 

'JHIVERSIIY  of  ILLINOIS. 


MARYLAND  GEOLOGICAL  SURVEY 


57 


Glauconite  seldom,  if  ever,  occurs  pure  in  nature,  but  is  mixed  with 
greater  or  less  amounts  of  arenaceous  materials,  producing  what  is 
known  as  greensand,  a term  which  is  commonly  made  to  embrace  the 
argillaceous  deposits  as  well,  particularly  when  the  glauconite  grains 
are  visible,  although  they  are  more  correctly  green  clays.  AVhen  the 
deposits  are  distinctly  calcareous,  they  are  generally  known  as  green- 
sand marls.  Xo  definite  percentage  of  any  of  the  constituents  is  re- 
quired, and  as  they  are  so  commonly  intermingled  the  terms  just  des- 
cribed are  used  somewhat  indiscriminately. 

DEPTH  OF  SEDIMENTATION. 

The  depth  at  which  sedimentation,  as  shown  by  the  existing  Eocene 
strata,  took  place  cannot  be  definitely  determined,  but  the  character 
of  both  the  deposits  and  the  fauna  points  to  seas  of  moderate  depth, 
probably  from  100  to  300  fathoms  in  the  southern  portion  of  the  area; 
while  the  ^coarser  and  less  glauconitic  materials  to  the  northward  sug- 
gest even  shallower  depths.  Bagg  reports  the  foraminifera  to  be  mainly 
of  shallow  water  types  while  the  other  classes  of  organisms  are  chiefly  of 
the  same  character. 

The  glauconitic  materials  of  which  the  formations  are  so  largely  coni- 
])osed  show  that  sedimentation  must  have  been  slow,  but  whether  this 
was  due  to  the  fact  that  the  deposition  went  on  far  from  the  shore-line 
or  to  the  fact  that  the  rivers  were  draining  a surface  approaching  base- 
level  cannot  be  satisfactorily  determined,  although  recent  work  on  the 
physical  history  of  the  Appalachian  region  since  the  Cretaceous  points 
to  the  latter  explanation  as  probable. 

Stratigrapiiical  and  Paleontological  Characteristics. 

The  Eocene  deposits  of  Maryland  and  adjacent  states  were  described  in 
1891  by  ]Mr.  X.  II.  Darton ' of  the  Y.  S.  Geological  Survey  under  the 
name  of  the  Pamnul'ey  formation,  ^lore  detailed  investigations  by  the 
authors  of  this  report  indicate  that  sufficient  lithologic  and  paleonto- 
logic  differences  exist  to  warrant  the  establishment  of  two  formational 
units  instead  of  one.  The  presence  of  an  argillaceous  bed  at  the  base 


> Bull.  Geol.  Soc.  Amer.,  vol.  ii,  1891,  p.  411. 


58 


THE  EOCENE  DEPOSITS  OF  MAKYLAND 


of  the  upper  member  has  been  shown  to  persist  very  generally  through- 
out the  area,  while  the  beds  above  and  below  are  sufficiently  distinct  as 
regards  their  lithologic  and  faunal  characteristics  to  be  distinguished 
readily  everywhere  by  the  geologist  in  the  field.  It  is  therefore  evident 
that  every  interest  will  be  subserved  by  the  establishment  of  two  forma- 
tions, and  they  will  be  thus  recognized  both  in  the  text  and  on  the 
accompanying  map.  Each  of  these  formations  also  represents  a well- 
defined  paleontological  stage  and  each  is  again  divided  into  two  clearly 
defined  members  or  substages,  and  the  latter  again  subdivided  locally 
into  zones. 

EOKMATIONS  AND  FAUNAL  STAGES." 

The  two  formational  units  of  the  Eocene  of  Maryland  are  known  as 
the  Aquia  foemation  and  the  Nanjemoy  foematton,  names  derived 
from  localities  in  the  Potomac  valley  where  the  deposits  of  each  division 
are  typically  developed.  Each  is  characterized  by  a well-marked  fauna, 
representing  a clearly-defined  paleontological  stage.^ 

The  formations  are  in  each  instance  divided  into  two  members  which 
represent  an  equal  number  of  paleontological  substages.  The  Aquia 
FOEMATION  is  divided  into  a basal  Piscataway  member  or  substage,  and  an 
overlying  Paspotansa  member  or  substage;  and  the  ETanjemoy  foema- 
tion is  divided  into  a lower  Potapaco  member  or  substage  and  an  upper 
Woodstock  member  or  substage. 

These  various  divisions  are  shown  in  the  following  table: 


Group. 

Formations  or  Stages. 

Members  or  Substages. 

r 

1 

Nanjemoy.  ' 

f Woodstock. 
1 Potapaco. 

Pamunkey. 

1 

1 

j Paspotansa. 

i 

Aqnia.  ( 

1 Piscataway. 

1 In  discussing  tlie  various  divisions  of  the  Maryland  Eocene  deposits  a distinction  is 
drawn  between  stratigraphic  and  paleontologic  units  ; the  former  are  designated  as 
formations  and  members,  the  latter  as  stages  and  substages.  As  their  limits  are  the 
same  the  same  name  is  employed  for  each. 

2 The  senior  author  in  an  earlier  publication  (U.  S.  G.  S.,  Bull.  141,  p.  39)  divided  the 
Pamunkey  on  the  basis  of  its  contained  fauna  into  the  Aquia  and  Woodstock  stages. 
Later  investigation  has  shown  that  the  fauna  from  the  Woodstock  beds  constitutes 
simply  a substage,  and  that  this  fauna  together  with  the  fauna  more  lately  discovered 
in  the  underlying  beds,  and  called  the  Potapaco  substage,  comprises  a larger  division 
now  termed  the  Nanjemoy  stage  and  formation. 


MAEYLAXD  GEOLOGICAL  SURVEY 


59 


Several  species  have  been  found  vdiicli  are  common  to  all  the  substages 
of  the  Pamnnkey.  They  are: 

Vohitilithes  peirosus  (Conrad).  Corbula  oniscus  Conrad. 

Calyptraea  aperta  (Solander).  Tellina  virginiana  Clark. 

Cadulus  ahruptus  Meyer  and  Aldrich.  2Iodiolus  alabamensis  Aldrich. 

Still  other,  forms  are  found  in  both  the  Aquia  and  Nanjemoy  stages, 
although  not  recognized  in  all  the  snbstages.  The  following  species 
have  been  found  in  the  Piscataway,  Paspotansa,  and  Potapaco  snbstages, 
but  are  not  known  in  the  Woodstock,  viz.: 

Tornatellaea  beUa  Conrad.  Lunatia  maryJandica  Conrad. 

Cylichna  venusta  Clark.  Ontrea  {Gryphaeostrea)  vomer  (Morton). 

The  following  have  been  found  in  the  Paspotansa  and  Potapaco  sub- 
stages, viz.: 

CaJyptraphorus  trinodifertis  Conrad.  Dentalium  mississippiensis  Conrad. 

The  following  form  ranges  from  the  Paspotansa  through  the  Potapaco 
and  Woodstock  substages,  viz.: 

Pecten  choctavensis  Aldrich. 


The  following  forms  have  been 
potansa  and  Woodstock,  viz.: 

Myliobatis  copeanus  Clark. 

Odontaspiff  cnspidata  (Agassiz). 
Strepsidura  mbscalarina  Heilprin. 
Corbula  subengonata  Dali. 

Protocardia  lenii<  Conrad. 


found  only  in  the  Piscataway,  Pas- 

Lucina  uJileri  Clark. 

GucuUaea  gigmitea  Conrad. 

Nodosaria  bacillum  Defrance. 
Polymorphina  gibba  d’Orbigny. 
Truncatulina  ungeviana  (d’Orbigny). 


The  Aquia  Formation  or  Stage. 

The  Aquia  formation,  so-called  from  Aquia  Creek,  which  enters  the 
Potomac  river  from  the  Virginia  side  about  fifty  miles  below  Washing- 
ton, is  composed  chiefly  of  greensands  and  greensand  marls,  at  times 
highly  calcareous  and  less  frequently  argillaceous.  The  various  litho- 
logical and  paleontological  characteristics  are  clearly  shown  in  the  de- 
tailed sections  which  follow.  The  deposits  reach  about  100  feet  in  thick- 
ness, gradually  thickening  eastward.  The  name  Aquia  was  originally 
employed ' to  embrace  the  faunal  stage  represented  by  Zones  2 to  9. 


•Johns  Hopkins  Univ.  Circ.,  1895,  p.  3;  Bull.  141,  U.  S.  Geol.  Survey,  1896,  p.  39. 


60 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


To  these  may  be  temporarily  added  Zone  1,  which^  so  far  as  known,  is 
devoid  of  determinable  fossils,  although  indeterminate  mollnscan  casts 
and  plant  remains  have  been  found  near  the  base  of  the  zone.  It  is 
possible  that  this  zone  should  be  made  an  independent  stage,  and  it  is 
not  improbable  that  it  may  represent  a definitely  lower  Eocene  horizon 
than  the  more  fossiliferous  beds  which  overlie  it,  but  in  the  absence  of 
distinctive  fossils  it  is  impossible  to  definitely  characterize  it.  It  may 
be  regarded  at  present  at  least  as  the  basal  zone  of  the  Aqnia. 

The  Aqnia  stage  contains  an  extensive  fauna.  Among  the  forms  that 
are  found  in  both  substages  are  the  following: 


Thecachampsa  sp. 

Thecachampsa  marylandica  Clark. 
Cy there  marylandica  Ulrich. 
Volutilithes  i>p. 

Caricella  pyruloldes  (Conrad). 
Turritella  mortoni  Conrad. 
Turritella  humerosa  Conrad. 
Vermetus  sp. 

Solarium  sp. 

Scala  virginiana  Clark. 

Gibbula  glandula  (Conrad). 
Gastrochaena  sp. 


Panopea  elongata  Conrad. 

Meretrix  ovata  var.  pyga  (Conrad). 

Lucina  aquiana  Clark. 

Venericardia  planicosta  var.  regia  Conrad. 
Crassatellites  alaef ormis  Conrad. 
Crassatellites  aquiana  Clark. 

Ostrea  compressirostra  Say 
Leda  cliftonensis  Clark  and  Martin. 
Trochocyaihus  clarkeanns  Vaughan. 
Eupsammia  elaborata  (Conrad). 

Nodosaria  communis  (d’Orbigny). 


Other  species  are  restricted  to  one  or  the  other  of  the  substages  and 
are  mentioned  beyond.  Additional  to  these  are  the  forms  previously 
referred  to  as  found  in  both  divisions  of  the  Pamunkey  group. 

The  Aquia  formation  has  been  divided  into  two  members  which  are 
clearly  separated  by  their  contained  faunas  over  considerable  portions 
of  Maryland  and  Virginia.  They  are  known  respectively  as  the  Pis- 
cataway  and  Paspotansa  members  or  substages. 


THE  PISCATAWAY  MEMBER  OR  SUBSTAGE. 

The  Piscataway  member,  so-called  from  Piscataway  Creek  which 
empties  into  the  Potomac  river  on  the  Maryland  bank  about  ten  miles 
below  the  city  of  Washington,  is  characterized  by  greensands  and  green- 
sand marls,  the  lower  beds  often  quite  argillaceous.  Two  well-marked 
and  rather  persistent  layers  of  indurated  marl  characterize  the  upper 
beds  in  the  Potomac  region.  The  Piscataway  member  generally  ex- 
ceeds 50  feet  in  thickness. 


MARYLAND  GEOLOGICAL  SURVEY 


G1 


The  PiscalaM’av  substage  is  limited  to  Zones  1 to  T.  The  fossils 
restricted  to  this  horizon  are: 


Xiphias  radiata  Clark. 

The  various  zones  of  this  division  in  the  Potomac  region  are  charac- 
terized as  follows: 

Zone  1. — The  thickness  of  the  Eocene  deposits  beneath  the  lowest  beds 
holding  the  typical  Aqnia  fauna  has  been  variously  estimated  up  to  60 
feet.  Some  exposures  are  seen  in  the  ravines  to  the  west  of  the  bluff, 
but  no  complete  sequence  of  the  beds  has  been  found.  xA.t  some  points 
the  strata,  scarcely  exceed  10  feet,  and  at  Glymont  the  beds  are  only 
8 feet  in  thickness.  They,  hov'evei,  gradually  increase  in  thickness  sea- 
ward; The  almost  entire  absence  of  fossils  renders  the  faunal  relations 
obscure.  The  poorA  preserved  animal  and  plant  remains  are  of  prac- 
tically no  value,  and  provisionally  this  bed  is  left  as  an  indeterminate 
basal  zone  of  the  Aqnia.  The  materials  are  greensands,  frequently 
quite  argillaceous  and  vuth  a basal  pebble  lied  overlying  the  Cretaceous 
at  some  points. 

Zone  2. — This  zone  is  characteristically  developed  both  at  the  base  of 
the  Aqnia  Creek  section  and  also  on  the  opposite  liank  of  the  Potomac 
river  at  Glymont.  The  beds  are  from  12  to  20  feet  in  thickpess,  and 
entirely  disappear  below  the  M’ater-line  a little  beyond  the  middle  of  the 
Aqnia  Creek  Iduff.  The  dark  greensand  of  udiich  the  zone  is  mainly 
composed  is  packed  with  the  sliells  of  Crassatellites  alaeformis  and 
Dosiniopsis  leiiticularis,  viiile  Tnrritella  mortoni,  T.  Immerosa,  Crassa- 
tellites aquiana,  Meretrix  orata  var.  pijga,  Cucullaea  gigantea,  and  Ostrea 
compressirostra  also  occur. 

Zone  3. — The  limestone  ledge  composing  this  bed  is  much  less  per- 
sistent than  in  the  overlying  limestones.  Zone  5,  and  at  times  it  nearly 
or  quite  disappears.  It  is  from  2 to  3 feet  in  thickness,  highly  glau- 


Thecachampm  aericodon  (:•*)  Cope. 
Thecachampaa  contnaov  Cope. 
End  antes  sp. 

Trionyx  viryiniaua  Clark. 
Synechodas  chirkii  Eastman. 
Odontaspis  rnacrota  (Agassiz). 
Odontaspis  elegans  (Agassiz). 
Odotus  obliqiiHs  (Agassiz). 

Sphy nia  prisca  Agassiz. 


Tndida  sp. 

Phenacoinya  petrosa  (Conrad). 

Pholadomya  marylandica  Conrad. 
Lithophaga  marylandica  Clark  and  Martin. 
Ostrea  compressirostra  var.  aJepidota  Dali. 
Gryphaea  vesicnlaris  Lamarck. 

Terehratula  harlani  Morton. 

Textalaria  suhangulata  d’Orbigny. 
Vaginulina  Jegumen  (Linne). 


62 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


conitic,  and  of  dark  color^  and  is  filled  with  shells  or,  more  commonly, 
casts  of  shells,  among  which  the  forms  of  Zone  2 are  conspicuous, 
together  with  Ostrea  compressirostra  and  Turritella  mortoni  in  larger 
numbers  than  in  the  lower  beds. 

Zone  Jf. — This  zone  is  composed  of  a highly  typical  greensand,  con- 
taining in  the  main  the  forms  mentioned  above  as  occurring  in  zones 
2 and  3.  It  is  from  7 to  9 feet  in  thickness. 

Zone  5. — This  limestone  bed  is  very  persistent  and  forms  a conspicu- 
ous ledge  about  2 feet  in  thickness,  along  the  face  of  the  Aquia  Creek 
bluff  until  it  passes  below  tide-water  near  its  eastern  extremity.  In 
addition  to  the  species  already  mentioned  as  characteristic  for  Zones  2 
to  4,  which  still  remain  common  forms,  there  are  two  highly  typical 
species,  viz.:  Plioladomya  marylandica  and  Phenacomya  petrosa,  as  well 
as  two  or  three  gasteropods,  Tudicla  sp.,  Caricella  sp.,  which  from 
the  fact  that  they  have  only  been  found  in  the  form  of  casts  cannot  be 
further  identified. 

Zone  6. — This  thin  layer,  generally  about  1 foot  in  thickness,  of  dark 
characteristic  greensand,  is  packed  with  the  common  forms  of  the  pre- 
vious beds.  It  thickens  somewhat  to  the  eastward  along  the  face  of 
the  bluff,  and  near  Marlboro  Point  contains,  among  other  forms,  several 
species  of  corals,  including  Eupsammia  elaborata,  Turbinolia  acuticos- 
tata,  and  Trocliocyatlius  clarTceanus. 

Zone  7. — The  bed  of  greensand  overlying  the  preceding- layer  is  really 
a continuation  of  it,  although  the  fossils  are  few  in  number  and  much 
broken.  Fragments  of  the  common  forms  of  previous  beds  are  found. 
This  bed  is  about  7 feet  thick.  It  is  barely  possible  that  this  stratum 
of  worn  and  broken  shells  represents  an  unconformity  between  the  Pis- 
cataway  and  Paspotansa  members.  Of  this,  however,  there  is  no  positive 
evidence  as  yet,  and  we  can  only  call  attention  to  the  fact  that  there  are 
physical  indications  of  more  disturbed  conditions  of  sedimentation  than 
are  usual  in  these  formations  at  the  very  point  where  the  faunal  change 
occurs. 

THE  PASPOTANSA  MEMBER  OR  SUBSTAGE. 

The  Paspotansa  member,  so-called  from  Paspotansa  Creek,  which 
enters  the  Potomac  river  from  the  Virginia  bank,  a mile  below  Potomac 


MARYLAXD  GEOLOGICAL  SURVEY 


63 


Creek,  is  composed  of  a thick  bed  of  greensand,  overlain  by  thick-bedded, 
indurated  layers  of  greensand  marl.  It  is  generally  somewhat  under  50 
feet  in  thickness. 

The  Paspotansa  substage  includes  Zones  8 and  9.  The  following 
fossils  are  restricted  to  this  suhstage: 


Bijthoeypris  subaequata  Ulricli* 

Bythocypris  parilis  Ulrich. 

Cytherella  tnm'Iboroensis  Ulrich. 

Cytherella  submarginata  Ulrich. 

Cythereis  basderi  Ulrich. 

Pleurotoma  harrisi  Clark. 

Plenrotoma  potonuicensis  Clark  and  Martin. 
Pleurotoma  ducateli  Clark  and  Martin. 
Pleurotoma  childreni  Lea. 

Pleurotoma  piscatavensis  Clark  and  Martin. 
Plexirotoma  tysoni  Clark  and  Martin. 
Cancellaria  graciloides  Aldrich  var. 
Cayicellaria  sp. 

Cancellaria  potomacenMn  Clark  and  Martin. 
Mitra  marylandica  Clark. 

Mitra  pomonkensis  Clark  and  Martin. 
Latirus  marylandicus  Clark  and  Martin. 
Fusus  subtenuis  Heilprin. 

Trophon  sublevis  Harris. 

Melongena  potomacensis  Clark  and  Martin. 
Tudicla  marylandica  Clark  and  Martin. 
Metula  marylandica  Clark  and  Martin. 
Chrysodomus  engonatus  (Heilprin). 
Pseudoliva  sp. 

Tritonium  showalteri  (Conrad). 

Fusoficula  juvenis  (Whitfield). 

Morio  brevidentata  (Aldrich). 
Calyptraphorus  jacksotii  Clark. 

Aporrhais  potomacensis  Clark  and  Martin. 
Litiopa  marylandica  Clark  and  Martin. 
Scala  potomacensis  Clark  and  Martin. 

Scala  sessilis  Conrad. 

Scala  carinata  Lea. 

Turbonilla  potomacensis  Clark  and  Martin. 
Odostomia  trapaquara  (Harris). 

Niso  umbilicata  (Lea). 

Calliostoma  sp. 

Fissuridea  marylandica  Clark  and  Martin. 

The  two  zones  recognized  in  the 
follows: 


Dlplodonta  marlboroensis  Clark  and  Martin. 
Crassatellites  alia  (Conrad). 

{?)  Astarte  marylandica  Clark. 
Coralliophaga  brya7ii  Clark. 

Pecten  sp. 

Platidia  marylandica  Clark  and  Martin. 
Discosparsa  varians  Ulrich. 

Fascipora  subramosa  Ulrich. 

Reticulipora  dichomata  Gahb  and  Horn. 
Cavaria  dumosa  Ulrich. 

Heteropora  tecta  Ulrich. 

Membranipora  rimulata  Ulrich. 
Alembranipora  spiculosa  Ulrich. 
Jfembra7tipora  angusta  Ulrich. 

Biflustra  to7'ta  Gabb  and  Horn. 

Eschara  digitata  Gabb  and  Horn. 

L7i7i7ilites  reversa  Ulrich. 

Cribrilina  modesta  Ulrich. 

Ci'ibrilina  crassula  Ulrich. 

Lepralia  S7ibpla7ia  Ulrich. 

Lepralia  labiosa  Ulrich. 

Mucronella  aspera  Gabb  and  Horn. 
Parac7jathus  ma7'ylandicus  Vaughan. 
Bala7ioplx7jllia  desmophyllum  Milne-Ed- 
wards  and  Haime. 

Texttdai'ia  gramc7i  d’Orbigny. 

TexUilaria  sagittula  Defrance. 

Fodosaria  consorbrina  var.  emaciata  Reuss. 
Nodosaria  sandbei'geri  (Reuss). 

Fodosaria  obliqua  (Linne). 

Margin  ula  costata  (Batsch). 

Cristellaria  gibba  (d’Orbigny). 

C7'istella7'ia  rotatula  (Lamarck). 
Poly7no7'phina  lactea  (Walter  and  Jacob). 
£Hscorbi7ia  tm'bo  (d’Orbigny). 

Anomalina  amrnonoides  (Reuss). 

Anomalina  grosserugosa  (Giimbel). 

Potomac  area  are  characterized  as 


64 


THE  EOCENE  DEPOSITS  OF  MAKYLAND 


Zone  8. — The  highly  characteristic  greensands  and  greensand  marls 
of  the  preceding  zones  are  succeeded  in  the  Potomac  sections  hy  a zone, 
some  30  feet  in  thickness,  in  which  the  grains  of  glauconite  have  been 
extensively  weathered  when  exposed,  giving  the  strata,  where  outcrops 
are  found,  a greenish-gray  appearance,  which  changes  to  a reddish- 
hrown  in  the  upper  layers.  Several  irregular  hands  packed  with  Turri- 
tella  mortoni  are  present  in  both  the  Aquia  Creek  and  Potomac  Creek 
sections,  while  associated  with  that  species  at  both  localities  are  Turritella 
humerosa,  Cucullaea  gigantea,  Crassatellites  alaeformis,  Ostrea  compressi- 
rostra,  and  many  other  forms.  The  upper  portions  of  this  bed  have 
afforded  most  of  the  species  obtained  from  the  Potomac  Creek  bluff. 

Zone  9. — The  thick-bedded  limestone  layers  which  compose  this  zone 
are  almost  exclusively  made  up  of  the  shells  of  Turritella  mortoni,  form- 
ing a Turritella  rock.  (Plate  III,  Fig.  2.)  Between  the  indurated  layers 
are  interstratified  layers  of  unconsolidated  and  much  weathered  green- 
sand, which  contain  few  fossils  of  any  description.  G-reat  masses  of  this 
Turritella  rock  strew  the  shore  at  the  base  of  both  the  Aquia  Creek  and 
Potomac  Creek  bluff's.  The  bed  is  about  10  feet  thick  in  the  Aquia 
Creek  bluff,  but  reaches  17  feet  at  Potomac  Creek.  At  the  latter  locality 
it  consists  of  five  feet  of  limestone  at  the  base,  followed  by  five  feet  of 
greensand,  two  feet  of  limestone,  two  feet  of  greensand,  two  feet  of 
limestone  and  one  foot  of  yellowish  greensand.  The  fauna  of  Zone  9 is 
evidently  identical  with  that  of  Zone  8. 


The  Nanjemoy  Formation  or  Stage. 


The  FTanjemoy  formation,  so-called  from  N'anjemoy  Creek,  which 
enters  the  Potomac  river  from  the  Maryland  side  in  Charles  county,  just 
below  Maryland  Point,  is  composed  of  greensand,  often  highly  argil- 
laceous, and  less  frequently  calcareous  than  the  lower  beds,  and  with 
here  and  there  layers  containing  abundant  crystals  and  crystalline 


masses  of  gypsum.  The  thickness  of  the  deposits  is  about  125  feet. 
The  Nanjemoy  stage  comprises  Zones  10  to  17.  The  following  fossils 


are  found  in  both  substages: 

Meretrix  ovata  var.  ovata  (Rog'ers). 

Lucina  dartoni  Clark. 

Lncina  wlntei  Clark. 

Venericardia  potapacoemis  Clark  & Martin. 
Ostrea  sellaeformis  Conrad. 


Lcd<(  improcera  (Conrad). 

Leda  potomacensis  Clark  and  Martin. 
Lcda  tysoni  Clark  and  Martin. 

Xncula  potomacensis  Clark  and  Martin. 


MARYLAND  GEOLOGICAL  SURVEY 


EOCENE,  PLATE  V 


THICKNESS 

IN  FEET  ZONE 


Greensand,  with  Ostrea  sellaeformis,  Meretrix  subimpressa, 

Venericardia  poiapacoensis,  etc. so 


Greensand,  with  few  fossils,  chiefly  Venericardia  potapa- 

coensis, - 4o 


Greenish-p:rey  argillaceous  sand  with  inconstant  indurated 
layer  at  top  and  with  many  typical  fossils. 


Greenish-gray  argillaceous  sand,  with  bands  of  gypsum  crystals,  - 
Light-gray  greensand,  with  Venericardia  potapacoensis. 

Greenish-gray  argillaceous  sand, 

Indurated  argillaceous  greensand, 


Argillaceous  greensand  with  clay  bed  at  base, 


Interstratified  indurated  layers  and  greensands  with  many 

Turritella  morioni,  i7 


Light  greenish-gray  greensand,  with  Turritella  mortoni^ 
CucuUaea  gigantea,  Crassatellitesalaeformis,  Ostrea  com- 
pressirostra,  etc., 


Greensand,  with  fragments  of  shells  of  lower  beds. 

Greensand,  with  corals,  

Ind.  greensand,  vf\t\xPholadomyamarglandica,&  Phenacomy  a petrosa. 

Greensand,  

Indurated  greensand, 

Dark  greensand  with  many  fossils,  including  Dosiniopsis 
lenticular  is,  Meretrix  ovata  var.pyga,  Crassatellites  alae- 
forrnis,  and  Ostrea  compressirostra, i 


Greensand,  at  times  argillaceous. 


Woodstock 

Member 


Paspotansa 

Member 


Piscataway 

Member 


GENERAL  COLUMNAR  SECTION  OF  EOCENE  STRATA  IN  MARYLAND 


Aquia  Formation  Nanjemoy  Formation 


MARYLAND  GEOLOGICAL  SURVEY 


65 


Other  species  are  restricted  to  one  or  the  other  of  the  substages  of  the 
Nanjemoy  and  are  mentioned  beyond.  x\dditional  to  these  are  the  forms 
previously  referred  to  as  found  in  both  divisions  of  the  Pamunkey 
group. 

THE  POTAPACO  MEMBER  OR  SUBSTAGE, 

The  Potapaco  member,  so-called  from  the  early  name  of  Port  Tobacco 
Creek,  which  is  a corruption  of  the  word  Potapaco  found  on  the  Smith 
and  other  early  maps,  is  composed  of  greensand,  often  very  argillaceous 
and  at  times  gypseous.  The  clayey  character  of  the  member,  especially 
in  the  lower  bed,  is  in  marked  contrast  to  the  more  highly  glauconitic 
nature  of  the  Aquia  formation.  The  thickness  of  the  member  is  about 
60  to  65  feet. 

The  Potapaco  substage  embraces  Zones  10  to  15.  The  following 
species  are  restricted  in  range  to  it: 

Cypraea  smithi  Aldrich.  Teriploma  sp. 

Solen  lisbonensin  Aldrich.  Ceriopora  micropora  Goldfuss. 

(?)  Lucina  astartif  ormis  Aldrich. 

The  following  zones  constitute  the  subdivisions  of  the  Potapaco  in 
the  Potomac  area,  some  of  which  can  be  recognized  over  wide  areas: 

Zone  10. — The  greenish-gray  sand  which  overlies  the  Turritella  rock 
is  more  argillaceous  than  the  underlying  or  overlying  beds  of  the  Eocene. 
The  glauconite  grains  have  been  much  weathered  and  nearly  all  trace 
of  the  shell  substance  has  been  removed  from  the  few  forms  recognized. 
To  the  northeast  of  the  Potomac  area,  throughout  the  central  portion 
of  Southern  Maryland,  this  bed  becomes  a well-defined  clay,  as  at  Upper 
Marlboro,  and  has  been  referred  to  as  the  Marlboro  clay.  The  casts 
found  at  the  Potomac  Creek  bluff  are  chiefly  those  of  a Meretrix,  prob- 
ably Meretrix  ovata  var.  ovata.  An  indurated  layer,  near  the  middle  of 
the  zone,  contains  Calyptraphorus  trinodiferus ; below  this  is  the  repre- 
sentative of  the  red  clay  which  occurs  typically  about  Upper  Marlboro. 
No  fossils  were  observed  at  the  Aquia  Creek  bluff.  The  bed  is  about  25 
feet  in  thickness. 

Zone  11. — This  zone  is  composed  of  a thin,  indurated  layer  of  argil- 
laceous greensand,  1 to  2 feet  in  thickness.  It  is  well  developed  at  the 
Potomac  Creek  bluff,  where  it  contains  Venericardia  potapacoensis,  and 
is  the  lowest  horizon  at  which  this  species  has  been  found. 

5 


66 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


Zone  12. — A greenish-gray  argillaceous  sand,  containing  few  nn- 
weathered  grains  of  greensand.  No  fossils  have  been  found  in  it.  The 
bed  is  8 or  9 feet  thick. 

Zo7ie  13. — This  bed  consists  of  a light-gray  glauconitic  sand,  generally 
somewhat  weathered.  It  is  crowded  with  shells  of  Venericardia  potapa- 
coensis,  and  also  contains  Tornatellaea  bella,  Cadulus  dbruptus,  etc. 

It  is  3 feet  in  thickness. 

Zone  !!{-. — Overlying  the  Venericardia  layer  is  a bed  of  greenish-gray 
argillaceous  sand,  some  4 to  6 feet  in  thickness,  that  contains  a great 
number  of  bands  filled  with  gypsnm  crystals.  No  fossils  were  observed. 

Zone  15. — This  bed  consists  of  greenish -gray  argillaceons  sand,  in 
which  the  glauconite  grains  have  often  been  extensively  weathered. 
The  bed  has  a thickness  of  12  to  25  feet. 

At  various  localities  in  Charles  county,  notably  about  Port  Tobacco 
and  at  the  headwaters  of  Nanjemoy  Creek,  this  zone  contains  a fauna 
that  is  quite  distinct  from  either  the  Aquia  or  Woodstock  faunas.  It 
is  an  unweathered  greensand,  and  very  argillaceous  at  these  localities. 
The  top  of  the  bed  is  marked  by  a well-developed  layer  of  concretions. 
This  layer  passes  below  water-level  about  2J  miles  above  the  mouth  of 
Popes  Creek,  and  is  to  be  seen  about  six  feet  above  the  base  of  the  bluff 
at  Woodstock. 


THE  WOODSTOCK  MEMBER  OR  SUBSTAGE. 


The  Woodstock  member,  so-called  from  Woodstock,  which  is  an  old 
estate  situated  a short  distance  above  Mathias  Point  on  the  Virginia 
bank  of  the  Potomac,  is  characterized  by  fine,  homogeneous  greensands- 
and  greensand  marls,  that  are  less  argillaceous  than  the  underlying 
Potapaco  beds.  The  member  has  a thickness  of  50  to  60  feet. 

The  Woodstock  substage  embraces  Zones  16  and  17  and  contains  the  ’ 
following  species  in  addition  to  those  previously  mentioned  as  ranging 
throughout  the  Nanjemoy,  viz.: 


Carcharodon  auricnlalm  (Blainville). 
Gahocerdo  latidens  Agassiz. 

Olivula  sp. 

LeviftiHus  traheatns  (?)  Conrad. 
Levifnsus  trabeatns  (?)  var. 

Pyrnla  penita  Conrad,  var. 

Ptjrula  sp. 


{?)  Leda  par  ills  Conrad  var. 

Spiroplecta  clarki  Bagg. 

Nodomria  affinis  (d’OrbignjO. 

Cristellaria  radiata  Borneman. 
Polymorphina  austriaca  (d’Orbigny). 
Polymorphina  elegantissima  Parker  & Jones. 
Polymorphina  praelonga  Terquem. 


MARYLAND  GEOLOGICAL  SURVEY 


67 


Turritella  potomacensis  Clark  and  Martin.  GJohigerina  huUoides  d’Orbigny. 

Dentalium  minntistriatum  Gabb.  Discorhina  hertheloti  (d'Orbigny). 

Meretrix  lenis  (Conrad).  PulvinuUna  schreibersii  (d’Orbigny). 

(.^)  Jleretrix  subimpressa  (Conrad).  Xonio7iina  affinis  Reuss. 

(.^)  Lucina  astartif ormis  Aldrich.  Amphistegina  lessouii  d’Orbigny. 

Venericardia  marylandica  Clark  & Martin.  Cmpolithns  mcn'yJandiciifi  Hollick. 

2Iodiolus  marylandicus  Clark  and  Martin.  Carpolithus  i7iarylandicus  vcn\  r7tgosns 

Leda  parva  {Rogers).  Hollick. 

The  two  zones  comprising  the  Woodstock  in  the  Potomac  area  are 
characterized  as  follows: 

Zone  16. — In  this  zone  haA^e  been  placed  the  strata  intervening  he- 
ttveen  the  upper  layers  of  the  Potomac  Creek  section  and  the  base  of 
the  Popes  Creek  section.  The  deposits  are  estimated  to  reach  about 
40  feet  in  thickness,  and  are  chiefly  greensands  and  greensand  marls. 
They  appear  in  an  unfossiliferous  condition  in  some  of  the  raAunes  to  the 
Avest  of  the  Woodstock  area,  and  along  the  shores  Avhere  they  contain  a 
few  fossils  of  common  Woodstock  species. 

Zone  17. — The  highest  beds  at  AYoodstock,  and  the  Popes  Creek 
strata,  are  grouped  together  in  this  zone.  The  materials  are  very  homo- 
geneous, although  several  inconstant  indurated  layers  appear.  The 
thickness  of  this  zone  is  about  20  feet.  A thin  bed  of  Ostrea  sellaef ormis 
Avas  observed  in  the  lower  part  of  the  zone,  although  evidently  not 
ahvays  at  the  same  horizon.  OtherAvise,  so  far  as  ohserA^ed,  the  fossils 
are  the  same  in  the  several  parts  of  the  tAvo  sections.  The  most  common 
forms  are  Protocardia  lenis,  Glycymeris  idoneus,  Meretrix  subimpressa, 
Corbula  subengonata,  Corbula  oniscus,  Leda  cult  elli  for  mis,  Pecten  dalli, 
Leda  improcera,  Leda  parva,  Nucula  potomacensis,  Lucina  dardoni,  Lucina 
ulderi,  Lucina  wliitei,  and  Ringicula  dalli. 

LOCAL  SECTIONS. 

The  formations  and  faunal  stages  previously  described  are  based  on 
the  numerous  local  sections  found  scattered  throughout  the  Eocene 
area  of  Maryland.  The  most  numerous  and  complete  series  of  sections 
is  found  in  the  valley  of  the  Potomac  river,  hut  other  and  highly  im- 
portant sections  are  found  to  the  northAvard  nearly  to  the  DelaAvare  line. 

Potomac  River  Section. 

The  most  complete  section  of  the  Eocene  deposits  of  the  Middle 
Atlantic  Slope  is  found  in  the  valley  of  the  Potomac  river  hetAveen  Aquia 


68 


THE  EOCENE  DEPOSITS  OF  MAKYLAND 


Creek,  Stafford  county,  Va.,  and  Popes  Creek,  Charles  connty,  Md. 
Throughont  this  distance  the  bluffs  afford  a nearly  complete  sequence 
of  the  several  beds  of  the  formations,  while  the  fossils  are  numerous 
and  well-preserved. 

The  full  Potomac  Eocene  series  is  given  in  both  generalized  and  local 
columnar  sections  on  Plates  V and  YI.  The  former  is  made  up  chiefly 
from  the  local  sections  afforded  by  the  bluffs  at  Glymont,  Aquia  Creek, 
Potomac  Creek,  Nanjemoy  Creek,  Woodstock,  and  Popes  Creek,  but  con- 
tains additional  data  obtained  at  a few  points  inland. 

The  local  sections  are  presented  in  columnar  form  on  Plate  YI,  and 
the  numbering  corresponds  with  that  given  at  the  head  of  the  descrip- 
tions of  the  sections  which  follow.  The  numbering  of  the  zones  in  the 
general  section  is  the  same  as  that  in  the  local  sections.  The  unnum- 
bered zones  are  pre-  or  post-Eocene,  as  the  case  may  be. 


Pleistocene. 


I.  Section  at  Glymont^  north  of  wharf  and  ravine. 
Gravel  and  loam 


Feet. 

20 


Eocene. 


r Light  green  glauconitic  sand,  underlain  by  argillaceous 

sand,  with  few  fossils  (Zone  4) 

Indurated  greensand  (Zone  3)  

Greenish  marl  with  numerous  fossils  including  Ostrea  com- 
pressirostra,  Crassatellites  alaeformis,  Turritella  rnortoni.^ 
Dosinopsis  lenticular  is Meretrix  ovata  var.  pyga.,  etc. 

(Zone  2) ! 

Argillaceous  glauconitic  sand  for  the  most  part  without 
fossils,  but  containing  indeterminate  plant  remains  and 
molluscan  casts  at  the  base  (Zone  1) 


10 

1 


21 

8 


Cretaceous. 


Variegated  clays  of  the  Potomac  group, 


20 


Total 


80 


II.  Section  two  miles  up  Aquia  Creek. 


Feet. 


Pleistocene. 


Gravel  and  sand 


Eocene. 


, f I Indurated  greensand  (Zone  3) 

^ j Greensand  with  characteristic  fossils  (Zone  2) 

I Argillaceous  sand  more  or  less  glauconitic  without  fossils 
^ I (Zone  1) 

PL 


1 

15 

18 


Total 


41 


MARY 


EOCENE,  PLATE  VI 


:ac  valley 


MARYLAND  GEOLOGICAL  SURVEY 


EOCENE,  PLATE  VI 


LEGEND 

||£S  Nanjemoy  Formation 
I , “i  Aqula  Formation 


DETAILED  COLUMNAR  SECTIONS  OF  EOCENE  STRATA  IN  THE  POTOMAC  VALLEY 


MARYLAND  GEOLOGICAL  SURVEY 


69 


Pleistocene. 


Eocene. 


<5 


III.  Section  of  western  portion  of  bluff  at  Aquia  Creek. 


Feet. 


Fine  sand,  liglit-yellow  in  color,  witli  white  clay  near  the 
base 26 


r Fine  sand,  of  light-greenish  color,  containing  a few  glau- 
conitic grains  (Zone  10) 

Thick-bedded,  arenaceous,  and  glauconitic  limestone  inter- 
stratifled  with  unconsolidated  layers  of  partially  weathered 
greensand,  the  indurated  layers  largely  filled  with  the 

shells  of  Turritella  mortoni  (Zone  9) 

Fine  sand,  of  gray  or  green  color,  containing  several 
irregular  bands  of  Turritella  mortoni.,  also  T.  humerosa., 
Cucullaea  gigantea.,  Crassatellites  alaeformis  and  Ostrea  com- 
pressirostra  (Zone  8) 


10 


10 


30 


Oj 


Dark-colored  greensand,  chiefly  filled  with  broken  shells  of 
Meretrix  ovata  var.  pyga  and  Crassatellites  alaeformis  (Zone  7)  7 

Ditto,  with  same  shells  in  whole  condition  (Zone  6) 1 

Indurated  layer  of  light-colored  greensand  filled  with 
Turritella  mortoni.,  T.  humerosa.,  Crassatellites  alaeformis., 
Dosiniopsis  lenticularis,  Meretrix  ovata  var.  pyga,  Panopea 

elongata,  Pholadomya  marylatidica  (Zone  5) 2 

Greensand  marl  containing  same  forms  (Zone  4) 8 

Indurated  layer  of  dark-colored  greensand  with  Crassatellites 
alaeformis,  Meretrix  ovata  var.  pyga,  Dosiniopsis  leiiticularis, 

and  Ostrea  compressirostra  (Zone  3) 2 

Greensand  marl  with  Dosiniopsis  lenticularis,  Meretrix  ovata 
var.  pyga  and  Crassatellites  alaeformis  (Zone  2) 16 


Total 


112 


IV.  Section  of  center  of  bluff  at  Potomac  Creek. 

Feet. 


Pleistocene.  Fine  yellowish  sand  containing  red  and  brown  bands 15 

Neocene.  White  gritty  clay,  with  Miocene  fossils  at  base 5 


Eocene. 


ii 


Greenish-gray  argillaceous  sand,  slightly  glauconitic  (Zone 

15) 38 

Argillaceous  sand  containing  bands  of  selenite  crystals 

(Zone  14) 4 

Light-gray  glauconitic  sand  with  Venericardia  potapacoensis 

(Zone  13) 3 

Greenish-gray  argillaceous  sand  (Zone  12) 8 

Indurated  greensand  with  Venericardia  potapacoensis  (Zone  11)  1 

Greenish-gray  argillaceous  sand,  glauconitic,  with  casts  of 
Meretrix  (Zone  10) 25 


' Thick-bedded  arenaceous  and  glauconitic  limestone  inter- 
f jj-  stratified  with  layers  of  partially  weathered  greensand, 
j g the  indurated  strata  largely  composed  of  the  shells  of 

J ^ Turritella  mortoni  (Zone  9) 12 

] * Greensand  bed,  much  weathered  in  its  upper  portions,  and 

I ^ I filled  chiefiy  with  Turritella  mortoni  in  several  thick  layers; 
l^P-i  also  T.  humerosa,  Cucullaea  gig antea,  Cras.satellites  alaeformis, 

( Ostrea  compressirostra,  and  many  other  species  (Zone  8)  . . . 25 


Total 


136 


70 


THE  EOCEXE  DEPOSITS  OF  MARYLAND 


Pleistocene. 


Eocene. 


V.  Section  three  miles  below  Potomac  Creek.  ^ . 

Feet. 

Sand  and  gravel 2 

["  Greenish-gray  argillaceous  sand  (Zone  15).  . . 4 

Greenish-gray  argillaceous  sand  with  gypsum  crystals  (Zone 

14) 5 

^ Light  gray  greensand  with  band  containing  Venericardia 

potapacoensis  (Zone  13) 4 

Greenish-gray  argillaceous  sand  (Zone  12) 10 

Indurated  greensand  with  Vetiericardia potapacoensis  (Zone  11)  1 


Total 


26 


VI.  Section  at  Head  of  Nanjemoy  Creek. 

Feet. 


Pleistocene.  Sand  and  gravel 4 

t;,  ^ f Greenish-gray  argillaceous  sand  with  layers  containing 

g ^ j Venericardia  potapacoensis  (Zone  15) 11 

Eocene.  | Light  gray  greensand  with  gypsum  beds  (Zone  14) 6 

? [ Light  gray  greensand  with  Venei'icardia potapacoensis  (Zone  1^)  3 

^ p_(  Covered  to  tide 75 

Total 99 


Pleistocene. 


Eocene. 


a g 


VII.  Section  three  miles  above  Popes  Creek. 

Gravel  and  sand 

I Argillaceous  greensand  (Zone  15) 

\ Greensand  with  gypsum  crystals  (Zone  14).. 

[ Total 


Feet. 

3 

6 

5 

14 


VIII.  Section  two  and  one-quarter  miles  above  Popes  Creek. 


Feet. 


Neocene.  Diatomaceous  earth 


Eocene. 


{Greensand  with  fossil  casts  (Zone  17)  

Greensand,  somewhat  argillaceous  (Zone  16) 

L Grayish  black  argillaceous  greensand  (Zone  15)  with  num- 
J erous  bands  of  Venericardia  potapacoensis  an^  other  fossils, 
( overlaid  by  a band  of  concretions 


10 

10 

30 


5 


Total, 


55 


IX.  Section  of  center  of  bluff  at  Woodstock. 


Pleistocene.  Yellow  and  orange-colored  sands  and  gravel 25 

Neocene.  Diatomaceous  earth  with  Miocene  fossils 5 


Eocene. 


r.r 


Argillaceous  greensand  (Zone  17) 

Dark  greensand  more  or  less  argillaceous  with  Mitra  potoma- 
censis,  Strepsidura  subscalarina.^  Turritella  potomacensis., 
Mesalia  obruta,  Corbula  oniscus^  Meretrix  subimpressa.^  Pro- 
tocardia  lenis^  Pecten  dalli,  Ostrea  sellaeformis,  Glycymeris 
idoneus  and  Leda  cultelliformis  (Zone  16) 

Greensand  Avith  Tornatellaea  bella.,  Cylichna  venusta,  Ringicula 
dalli,  Venericardia  potapacoensis  and  other  forms  (Zone  15) 

Total  


6 


20 


6 

62 


MARYLAND  GEOLOGICAL  SURVEY’ 


71 


Neocene. 


Eocene. 


X.  Section  of  bluff  one  mile  below  Popes  Creek. 

Feet.  Inches. 


Diatomaceous  earth 40 

' Brown  glauconitic  clay  much  oxidized  in  places.  ...  2 

Band  of  pinkish-brown  clay  nodules  in  glauconitic 

clay 0 6 

Dark  glauconitic  clay  with  many  fossil  casts 4 

Concretions  with  occasional  fossils 0 6 

Argillaceous  greensand  with  many  casts  and  occa- 
sional shells 3 

-I  Concretions  with  many  large  specimens  of  Herco- 

glossa  tuomeiji 0 6 


Argillaceous  greensaud  with  abundant  fossils  in- 
cluding Jferetrix  subimpressa.,  Venericardia  potapa- 
coensis,  Hercoglossa  tuomeyi.,Turritella  potomacensis, 
Mesalia  obruta,  Protocardia  lenis,  Modiolus  alabam- 
e?isis,  Corbula  subengonata.,  Mitra  potomacensis,  and 
many  other  fDrms  (Zone  17) 6 


Total 


56  6 


Other  Sections. 

Along  none  of  the  other  drainage  lines  is  the  sequence  of  Eocene 
strata  as  complete  as  in  the  Potomac  river  area.  Several  important 
local  sections,  composed  of  one  or  more  members  of  the  series,  have 
been  observed  at  many  different  points  and  may  be  correlated  with  one 
or  the  other  of  the  divisions  previously  referred  to.  Some  of  the  more 
important  and  typical  sections  follow. 


Section  in  ravine  three-quarters  of  a mile  east  of  Oxen.,  Prince  George's  County. 


Eocene. 


Feet.  Inches. 


Yellow  glauconitic  sand 5 

Indurated  ledge 4 

Black  shell  marl 4 

Indurated  ledge  with  Ostrea  compressirostra 6 

Shell  marl,  lower  part  packed  with  soft  shells  in- 
cluding Cucullaea  gigantea^  Ostrea  compressirostra, 

Meretrix  ovata  var.  pyga  Dosiniopsis  lenticularis, 
Crassatellites  alaeforrnis,  Turritella  humerosa 10 


Total 


10 


Section  in  Railroad  cut  near  Seat  Pleasant,  Prince  George's  County. 

Feet. 

Pleistocene.  Gravel  and  loam 12 

r 

. g I Glauconitic  shell  marl  with  OsG-ea  5 


Eocene. 


Indurated  ledge  with  Ostrea  compressirostra..  Modiolus  alabam- 
ensis,  Crassatellites  alaeforrnis,  Corbula  sp.,  etc 8 


Total 


72 


THE  EOCENE  DEPOSITS  OF  MAKYLAND 


Eocene. 


Neocene. 


Eocene. 


Section 


o 


S 


east  of  bridge  at  Upper  Marlboro,  Prince  George's  County, 
f Feet. 


Glauconitie  clay 22 

Pink  clay,  without  glauconite  or  fossils 22 


Coarse  glauconitic  sand 32 

Shell  marl  with  Gibbida  glandula,  Fissuridea  marlboroensis, 
Lticina  aqtdana,  Diplodonta  marlboroensis,  Venericardia  plan- 
icosta  var.  regia,  Fteria  limula,  Cucullaea  gigantea,  Leda 

parilis,  Nucula  ovula 2 

Indurated  ledge  with  Turritella  mortoni,  T.  humerosa,  Mesalia 
obruta,  Calyptraphorus  jacksoni,  Panopea  elongata,  Meretrix 
ovata  var.  pyga  Dosiniopsis  lenticularis,  Venericardia  plani- 
costa  var.  regia,  Crassatellites  alaeformis,  Astarte  maryland- 
ica,  Glycymeris  idonens,  Cucullaea  gigantea,  Leda.  parilis, 

Nucula  ovula 

Glauconitic  sand  full  of  tine  fragments  of  shells  accompanied 
by  bryozoa,  echinoid  spines  and  foraminifera ; and  with 
Ostrea  compressirostra,  Gryphaeostrea  vorner,  and  Platidia 

(Known  as  Bryozoan  sand) 5 


Total 88 

Section  in  ravine  one  mile  south  of  Thrift,  Prince  George's  County. 

Feet.  Inches. 


Lead-colored  clay  with  Miocene  fossils 40 

" Dark  argillaceous  greensand 7 

Argillaceous  greensand, packed  with  Venericardia  po- 


tapacoensis 1 

Dark  glauconitic  clay 3 

Layer  of  Venericardia  potapacoensis 

Greensand  with  many  scattered  specimens  of  Vener- 
icardia potapacoensis 3 

Line  of  concretions 

Glauconitic  clay  with  Venericardia  potapacoensis 4 

Dark  greensand 5 


Layer  packed  with  shells  of  Venericardia  potapacoensis  1 


Argillaceous  greensand 1 

Line  of  concretions 

Argillaceous  greensand 3 

Greensand  with  Venericardia  potapacoensis 1 

Dark  glauconitic  clay 3 


Layer  of  shells  of  Venericardia  potapacoensis. 
[ Dark  clay,  with  much  glauconite 


8 

6 


4 


Total 


74  6 


Section  on  bank  of  Patuxent  River  one-quarter  mile  below  mouth  of  Lyons  Creek, 


Calvert  County. 

Pleistocene.  Sand  and  gravel 6 

<u  f Diatomaceous  clay 9 

^ S j Siliceous  indurated  stratum  with  Miocene  fossils  ...  10 

eocene.  o ^ Brown  gritty  clay,  with  abundant  casts  of  Miocene 

fossils 4 

o>  . ( Argillaceous  greensand,  with  abundant  casts  of 

Eocene.  'o’  ^ Nanjemoy  fossils 10 

3 ( Line  of  concretions 2 

Argillaceous  greensand  and  talus 20 

Total 50  0 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  VII 


Fm.  1.— LOWER  EOCENE  DEPOSITS  ON  SEVERN  RIVER. 


Fig.  2. -indurated  layer  at  UPPER  MARLBORO,  OVERLYING  BRYOZOAN  SAND. 


VIEWS  OF  EOCENE  SECTIONS. 


MARYLAND  GEOLOGICAL  SURVEY 


73 


Section  on  South  River  at  mouth  of  Broad  Creek^  Anne  Arundel  Cou7ity. 


Eocene. 


^ I 


Feet. 


Ferruginous  sandstone  full  of  casts  of  Turritella  mortoni^ 
Venericardia  planicosta  var.  regia,  Crassatellites  alaeformis, 

etc 10 

Coarse  oxidized  greensand  with  occasional  casts  of  Venericar- 
dia planicosta  var.  regia 34 

Talus 34 


Total 


58 


Section  on  north  hank  of  Severn  River  07ie  mile  above  railroad  bridge,  Anne  Arundel 
Coimty. 

Feet. 

Pleistocene.  Sand  and  loam 5 


Eocene. 


O"  oS 


[ Coarse  red,  glauconitic  sand  partially  indurated,  with  Ostrea 
I compressirostra,  Cucullaea  gigantea,  Aferetrix  ovata  var.  pyga, 

J Turritella  lyiortoni,  etc, 

i Red  glauconitic  sand  and  talus 


Total 


20 

50 

75 


Section  07i  Chester  River  opposite  Rolphs  Landing,  Kent  County. 


Feet. 


Pleistocene. 


Sand  and  loam 


Neocene  ? 


Drab  clay  with  a thin  band  of  limonite  at  the  base 


Eocene. 


pH 


Coarse  yellowish-red  glauconitic  sand  irregularly  indurated 
and  with  occasional  pockets  of  coarse  bright  green  glau- 
conitic sand 

Very  coarse  indurated  glauconitic  sand,  much  oxidized  and 
iron-stained,  with  abundant  angular  quartz  pebbles,  fre- 
quently % inch  in  diameter,  and  with  abundant  casts  of 
fossils,  including  Turritella  mortoni,  Panopea  elongata,  Pro- 
tocardia  lenis,  Venericardia  planicosta  var.  regia,  Crassa- 
tellites alaeformis,  Ghjcymeris  idoneus  and  Cucullaea  gigantea 
Oxidized  glauconitic  sand,  with  occasional  tubes  of  Vermetus 


5 

1 


4 


3 

7 


Total 


20 


Geological  and  Geographical  Distribution  of  Species. 

The  geological  and  geographical  distribution  of  the  species  obtained 
from  the  Maryland  Eocene  has  already  been  indicated  in  a general  way 
in  the  discussion  of  the  various  stages,  suhstages  and  zones.  A much 
more  complete  presentation  of  the  distribution  of  all  the  forms  is  given 
in  the  accompanying  tables  and  in  the  chapter  on  systematic  paleon- 
tology with  which  the  report  closes.  Any  further  attempt  at  a discus- 
sion of  the  subject  at  this  time  would  lead  to  much  needless  repetition. 


74 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


SPECIES. 

LOCAL  DISTRIBUTION. 

Aquia  Formation. 

PISCATAWAY  STAGE. 

PASPOTANSA  STAGE. 

1 Fort  Washington. 

Seat  Pleasant  (Railroad  cut).  I 

Brooks  estate,  near  Seat  Pleasant.  | 

Piscataway  Creek. 

1 Swan  Creek,  near  Piscataway. 

1 Glymont. 

1 Aquia  Creek. 

1 Liverpool  Point. 

1 Reedy  Run. 

1 Clifton  Beach. 

1 Wades  Bay.  I 

Leeland.  I 

Three  miles  west  of  Leeland. 

Collington.  j 

One  mile  N.  E.  of  Grimesville. 

Three  miles  W.  of  Pisgah. 

1 Winchester. 

1 Fredericktown  Cecil  Co.  I 

1 One  mile  N.  E.  of  Piscataway.  | 

1 Tinkers  Creek,  near  Piscataway.  | 

1 Pomonkey  Neck.  | 

1 One  mile  S.  E.  of  Mason  Springs.  | 

1 Potomac  Creek.  | 

1 Two  miles  below  Potomac  Creek. 

Paspotausa  Creek.  I 

Mattawoman  Creek.  I 

Upper  Marlboro.  | 

Hardesty. 

i 

'S 

1^ 

W 

0 

® 

® 

a 

§ 

0 

1 Between  Buena  Vista  and  Collington. 

Crownsville. 

t Two  miles  south  of  South  River. 

South  River  1 mouth  ot  Broad  Creek). 

South  River  (Sheckels  farmi. 

Annapolis.  I 

Severn  River. 

Rolphs  Landing. 

Harrisons  Landing. 

1 Southeast  Creek.  1 

Reptilia. 

* 

H: 

* 

: 

Pisces. 

* 

* 

* 

A.6tobcitis  ciTcuatus  Ag'assiz 

Syne.nhnd'U.K  eJarhii  astman  

* 

Cid.nnl.asi'pis  p,lp,gn,nR  (Ag-a.ssiy.i  

* 

* 

OdontaR'piR  m,n,p,rntn,  (Ag’assiy.'i  

* 

Odontaspis  cuspidata  (Agassiz)  

Otodv.x  rthliq'ii.ti.R  Ag-assiz 

* 

* 

* 

(In.rp.hn.rnd.nn,  n.ii.rip.iiln.itist  (Tlln  ) . . 

frPiJpDP.p.rd n Tnt.id.pnn  Agassiy.  . 

Rphyrnn,  prisp.n,  Agassi 7, 

JCipliiai^  ? rodinta  (Clark)  

* 

Arthropoda.  Ostracoda. 
HytbopAjpriR  f<uhn,p,qun,t n,  TTlrip.h  .... 

Hyl.hopifprifi  parilia  TTIrioh 

CidJiPrplln,  mnrlhnrnpnftisi  TTlriph.... 

(lythp.rpJ.ln,  suhm n.rgin n.t n,  TTlriph  .... 

Cythp,rp,  mn.ryln.n.d.ip.n.  TTlrip.h 

* 

Cythereis  bassleri  Ulrich 

(lythp,rid,p,n,  pp.rn.rp.'u.n.tn.  TTlriph  . . 

* 

Moelusca.  Cephalopoda. 
Tdprp.nglnftsn,  t.ii.nm.p.yi.  C',  At;  M 

Moleusca.  Gastropoda. 
'rnmn.l.plln.p.n,  hp.lln,  Ponrarl 

* 

* 

* 

* 

JiingiP'uln,  dnlJ/i.  iTIark 

Cylip.hnn,  vpn'u.s<tn.  Clark 

* 

* 

* 

* 

1 

Plpurotnma  hn.rrixi  Clark 

Plpurotomci  potoi7icice7isis  C & M 

* 

Plpurof  nmn,  dii,p.n.f  p.li  ( !.  A;  M 

* 

Plpii.rnt.nmn.  p'h.ildTP.'ni  T,pa  

* 

Plcurotonid  pisccvtdv&ns^is  C & M 

Pleurotomd  tysoui  C.  & M 

* 

Mdngilid  belli»t7’idtd  Clark 

* 

Cd,n,p,pMn,rin,  grdpAlnidPR  Aid  vn.r.... 

* 

Cdncclldrid  sp 

* 

C!n,nr.p,lln,rid  pnt.nmnp.pnxia  (1  M. . . . 

Olivuld  sp 

Volu.tilit.hps  ppt.rnsn.a  (fTnnrarl) 

* 

: 

* 

Volvt.ililhpR  ap  

Pdi'ipplld  pifrulnidpa  f Tnnnrfid)  . . 

* 

WTit.rn,  'nrn,ryl,n.n,d,ip,n.‘i  PI  ark 

* 

JVf  itA'd,  jmmnn'kpnaia  P At  M 

H: 

* 

TVntrn,  pnt.nmn.p.p.naia  P .itT  M ... 

Ldtii'us  m dry] d}) di.pua  C.  A?:  M 

t 

Viiati.a'^  aiiJyl.puii.ia  ITpilprin.  . . 

PiiS'na?  iiit.p.TatTini.ii.a  TIpilprin 

* 

* 

'Trnphnn  aiihlpi’^ia  Harris  . . . 

Strepsidtird  s^ibscdldi'inn  Heilprin. 

* 

* 

* 

Melongend'i  potonidcensis  C.  & M... 

MARYLAND  GEOLOGICAL  SYRYEY 


LOCAL  DISTRIBUTION. 


Nanjemoy  Eormation. 


Reptilia. 

Thecachampsa  sp 

Thecachampsa  sericodon  ? Cope 

Thecachampsa  contusor  Cope 

Thecachampsa  marylandica  Clark 

Euclastes  ^?sp 

Trionyjc  virginiana  Clark 

Pisces. 

Mijliobaiis  copeanus  Clark 

Akohatis  arcuatiis  Ag-assiz 

Synechodus  clarkii  Eastman 

ddontaspis  elegans  (Agassiz) 

Odontaspis  macrota  {Agassiz) 

Odontaspis  cuspidata  (Agassiz)  — 

Otodus  obliqiius  Agassiz 

Carcharodon  auriculatxis  (Bln).... 

Galeocerdo  Inlidens  Agassiz 

tiphyrtia  prisca  Agassiz 

Xiphias  f radiata  (Clark) 

Arthropoda.  Ostracoda. 
Bylhocypris  subaequcbf.a  L'lrich  ... 


Bythocypris  parilis  Ulrich  . 
Cytherella  marlboroensls  Ulrich  . 


Cytherella  submarginata  Ulrich., 

Cythere  marylandica  Ulrich 

Cythereis  bassleri  Ulrich 

Cylheridea  perarcuata  Ulrich  ... 

MoiiEUSCA.  Cephalopoda. 

Hercoglossa  tuomeyi  C.  & M 

Mollusca.  Gastropoda. 

Tornatellaea  bell  a Conrad 

Ringicula  dalli  Clark 

Cylichna  venusta  Clark 

Pleurntoma  harrisi  Clark 

Pleurotoma  potomacensis  C.  & M. 

Pleurntoma  ducateli  C.  & M 

Pleurotoma  childreni  Lea 

Pleurotoma  piscatavensis  C.  & M. 

Pleurotoma  tysoni  C.  & M 

Mangilia  bellisLriata  Clark 

Cancellaria  graciUndes  var.  Aid  . 

Cancellaria  sp 

Cancellaria  potomacensis  C.  & M.. 

Olivula  sp 

Volutilithes  petrosus  (Conrad) 

Volutilithes  sp 

Caricella  pyruloides?  (Conrad)  ... 

Mitra  marylandica  Clark  

Mitra  pomonkensis  C.  & M 

Mitra  potomacensis  C.  & M 

Latirus  marylandicus  C.  & M 

Fusus  ? subtenuis  Heilprin 

Fusus?  interstriatus  Heilprin 

Ti'ophon  sublevis  Harris 

Strepsidura  subscalarina  Heilprin 
Melongena?  potomacensis  C.  & M . 


!•« 

• (D 


I®  ^ 


Si*  I 

.do; 


e i o " 
2:« 

bi' 

eg  X! 

33  b ^ 


S 1 2 

^ O oS 

-V  O 


GENERAL  DISTRIBUTION. 


GULF  PROVINCE. 


1 Harris:  Bull.  Amer.  Pal.,  No.  4.  3 Harris  : Bull.  Amer.  Pal.,  No.  11. 

5 Harris  : Proc.  Acad.  N.  Sci.,  Phila.,  189.5, 


* Aldrich : Coastal  Plain,  Alabama. 


76 


THE  EOCENE  DEPOSITS  OF  MAKYLAND 


LOCAL  DISTRIBUTION. 


SPECIES. 


MoiiiiUSCA.  Gastropoda.— CoHt. 

Tudicla  marylandica  C.  & M 

Tudicla  sp 

Tudicla  ? sp 

Levifusus  traheatus  ? Conrad 

Levifusus  traheatus  ? var.  Conrad 

Mctula  marylandica  C.  & M 

Chrysodomus  engonatus  (Heilprini. 

Pseudoliva  sp 

Tritoniurn  showalteri  (Conrad) 

Pyrula  penita  var.  Conrad 

Pyrula?  sp 

Fulguroficus  argutus  Clark 

Fusoficula  juvenis  (Whitfield) 

Morio  hrevidentata  (Aldrich) 

Cypraea  smithi  Aldrich 

Calyptraphorus  jacksoni  Clark 

Calyptraphorus  trinodiferus  Con. . , 
Calyptraphorus  trinodiferus  ? var.. 

Aporrhais  potomacensis  C.  & M 

Turritclla  mortoni  Conrad 

Turritella  humerosa  Conrad 

Turritclla  potomacensis  C.  & M 

Mesalia  ohruta  (Conrad) 

Vermetus  sp 

Natica  cUftonensis  Clark 

Lunatia  marylandica  Conrad 

Calyptraea  aperta  (Solander)  

Litiopa  marylandica  C.  & M 

Solarium  sp 

Seala  virginiana  Clark 

Scala  potomacensis  C.  & M 

Seala  sessilis  Conrad 

Scala  carinata  Lea  

Turhonilla  potomacensis  C.  & M 

Tuba  marylandica  C.  & M 

Odostomia  trapaquara  (Harris)  

Niso  umbilicata  (Lea)  

Oibbula  glandula  (Conrad) 

Calliostoma  sp 

Fissuridea  marlboroensis  C.  M.  . . 

MotitiUSCA.  Scaphopoda. 
Dentalium  minutistriatum  Gabb... 

Dentalium  mississippiensis  Con 

Cadulus  abruptus  Meyer  & Aldrich. 

Mollusca.  Pelecypoda. 

Teredo  virginiana  Clark 

Phenacomya  petrosa  (Conrad) 

Oastrochaena  sp 

Panopea  elongata  Conrad 

Corbula  subengonata  Dali 

Corbula  aldrichi  Meyer 

Corbula  oniscus  Conrad 

Solen  Usbonensis't  Aldrich 

Tellina  virginiana  Clark 

Tellina  william, si  Clark  

Tellina  papyria  ? Conrad 

Meretrix  lenis  (Conrad) 


Aquia  Formation. 


PISCATAWAY  STAGE. 


PASPOTANSA  STAGE. 


Southi 


MARYLAND  GEOLOGICAL  SURVEY 


77 


LOCAL  DISTRIBUTION. 


Nanjemoy  Formation. 


S '3 

a 

® I 
■tJ  o ' . 
.H  cS  ® 


as  Ci 
^ S3  i . - 

3 u 


MOLLUSCA.  Gastropoda.— CoMt.  j 

Tudicla  marylandica  C.  & M 

Tudicla  .sp.  Conrad  

Tudicla^:!  sp ;• 

Levifusus  trabeatus  ( Conrad 

Levifusus  traheatus  var.  ? Conrad  . 
Metiila  marylandica  C.  & M.  ....... 

Chrysodomus  enyonatus  (Heilprin). 

PseudoUva  sp 

Tritonium  showalteri  (Conrad) 

Pyrula  penita  var.  Conrad 

Pyrula  V sp 

Fulguroficus  argutus  Clark 

FusoUcula  juvenis  (Whitfield) 

Morio  brevidentata  (Aldrich) 

Cypraea  smithi  Aldrich 

C^lyptraphnrus  jackMni  Clark 

Calyptraphorus  trinodiferus  Con... 
Calyptraphorus  trinodiferus  var  ?. . 
Aporrhais  potomacensis  C.  & M . . . . 

TurriteUa  mortoni  Conrad 

Turritella  humerosa  Conrad 

TurriteUa  potomacensis  C.  & M. . . 

Mesalia  obruta  ^Con^ad) 

Vermetus  sp 

Natica  cliftonensis  Clark 

Lunatia  marylandica  Conrad 

Calyptraea  aperta  (Solander) 

1 Litiopa  marylandica  C.  & M 

Solarium  sp 

Scala  virginiana  Clark  

1 Scala  potomacensis  C.  & M 

Scala  sessilis  Conrad 

Scala  carinata  Lea 

Turbonilla  potomacensis  C.  & M... 

Tuba  marylandica  C.  & M 

Odostomia  trapaguara  (Harris)  — 

Nixo  umbilicata  (Lea) 

Giblmla  glandula  (Conrad) 

Calliostoma  sp 

Fissuridea  marlboroensis  C.  & M.  . 

Mollusca.  Scaphopoda. 
Dentalium  minutistriaium  Gabb.. 
Dentalium  mississippiensis  Con — 
Cadulus  abruptus  Meyer  & Aldrich 

Moleusca.  Pelecypoda. 

Teredo  virginiana  Clark 

Phcnacomya  petrosa  (Conrad)  . 

Gastrochaena  sp 

' Panopea  elongata  Conrad  

Corbula  subengonata  Dali 

Corbula  aldrichi  Meyer  

Corbula  oniscus  Conrad 

Solen  lisbonensis'i  Aldrich 

Tellina  virginiana  Clark 

Tellina  williamsi  Clark 

Tellina  papyria  ? Conrad 

Meretrix  lenis  (Conrad 


t-  ® j 

ns® 

0 ^ A; 


NiS  ® 

II'® 

S'o'olS 


GENERAL  DISTRIBUTION. 


GULF  PROVINCE 


1 Harris:  Bull.  Amer.  Pal.,  No.  4.  2Harris:  Bull.  Amer.  Pal.,  No.  9.  3 Harris:  Bull.  Amer.  Pal.,  No.  11. 

* Aldrich : Coastal  Plain,  Alabama.  ® Harris : Proc.  Acad.  N.  Sci.,  Phila.,  1895.  ’ Dali : Trans.  Wag.  Free  Inst.,  vol.  iii,  pt.  v. 


THE  EOCENE  DEPOSITS  OF  MAEYLAND 


SPECIES. 

LOCAL  DISTRIBUTION. 

Aquia  Formation. 

PISCATAWAV  STAGE. 

PASPOTANSA  STAGE. 

1 Fort  Washing-ton.  1 

Seat  Pleasant  (Railroad  cut). 

Brooks  estate,  near  Seat  Pleasant. 

Piscataway  Creek. 

Swan  Creek,  near  Piscatawav. 

Glymont. 

Aduia  Creek. 

Liverpool  Point. 

Reedy  Run. 

1 Clifton  Beach. 

Wades  Bay. 

Leeland. 

Three  miles  west  of  Leeland. 

Collinffton. 

One  mile  N.  E.  of  Grimesville. 

.d 

cS 

K 

2 

o 

CO 

® 

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Winchester. 

1 Fredericktown,  Cecil  Co.  i 

i 

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s 

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Potomac  Creek. 

I'wo  miles  below  Potomac  Creek. 

1 Paspotansa  Creek. 

Mattawoman  Creek. 

Upper  Marlboro. 

Hardesty. 

One  mile  west  of  Hardesty. 

1 

Ql 

P 

1 
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Crownsville. 

1 Two  miles  south  of  South  River. 

South  River  (mouth  of  Broad  Creek). 

South  River  (Sheckels  farm). 

Annapolis. 

Severn  River. 

Rolphs  Landing-. 

Harrisons  Landing. 

1 Southeast  Creek.  | 

Mollusca.  Pelecypoda.— Co»tOiM6(L 

* 

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t 

i 

! 

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* 

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Luciucb  uhlci'i  Clark 

* 

H= 

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=(= 

7,11.0.11111,  inhif.o.i  Clark 

Lucinn  sp  

Venericardla  planicosta  var.  regia  Con. 
Vp.ii.p.vir.n.rriin,  mn.njln.indlp.n,  O.  A M 

* 

■■ 

* 

:(= 

* 

* 

H: 

* 

:(= 

Vp,ii.p.ri,p.n,rrlin,  'pntn.yin.p.np.n.sifi  (1  A,  IVT 

Crassatellites  alaetormif<  (Conrad) 

drn.siint.p.l.li.tp.st  n.qu.in.n.n,  (Olarkl 

> 

1 

1 

* 

:i: 

'=*= 

* 

I 

I" 

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(Irn.ssn.f.p.lli.t.p.fi  n.ltn.  ^rinnrad  i 

? 

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Crassatellites  sp  

Hc 

i:: 

Astn.rfp,  m.n.ryla.n.flip.n,  Cla,rk  

:i: 

* 

(Inrn.lllnphaga  hrijn.n.i  Clark  

r ■ 

* 

T*p,ripl,nm,a,  H .^p 

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1 

Ph.nln.rlnm.ifn,  mn.rifln.iifli.p.n,  Con 

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If nd.inlii.fi  n.ln.hn.mp.n.fiifi  Aid 

1 

* 

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L. 

'XTnrii, nl.ii.fi  m.n.ryl.n.na.ip.ii.ft  C.  A M 

T,i.t,hnjih.n.(fn,  m.n.ryl.n  n.di.p.n.  C \f 

* 

I" 

Annm.in,  m.n.ryln.n.rHp.n,  C AM  

Pp.p.t.p.ii.  p.h.np.t.n.i'ip.n si.fi  Aldrioh 

* 

=(= 

1 

Pp.p.f.p.n.  f1.n,l,l.i.  Clark 

* 

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=h' 

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Ostrea  compressirostra  Say 

Ostrea  compressirostra  var.  alepidota  Dali 
Ostrea  sellaeforinis  Conrad 

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=.= 

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Ostrea  {Gryphaeostrea)  vomer  (Morton) 

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frTijph.n.p.n.  1'ip.si.p.iil n.ri.s  T.amf^rok 

Pterin,  l.im.ii.ln  (Conrad  1 

* 

Gl.ijPifm.p.ris  i.dnn.eiis  (Conrarl)  ... 

* 

* 

* 

* 

•• 

Trigonoarca  decisa  (Con.)  var 

Cucullaea  gigantea  Conrad 

Leda  parva  (Rog'ors) 

* 

* 

:*= 

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H: 

? 

* 

:(= 

=(= 

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••1 

T,p,(1.n,  p.ii.l.f.p.l.l.i.fnrm  is  (Potyprsl 

..1 

Leda  improcera  (Conrad) 

1 

T iP.fl.n.  pn.riii.s  (ConrnH)  . . . 

* 

Leda  pai'iHs  var 

■ '1 

Leda  potomacensis  C.  & M 

! 

T,e(1.n.  pl.iftnnp.il sis  C A M 

:C 

* 

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..1 

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Leda  tysoni  C.  & M 

lVii.Pii.ln.  niMi.l.n.  T.oa 

1 

* 

Nucula  potomacensis  C.  & M 

I 

Molluscoidea.  Brachiopoda. 

'Terehrn.t.ii.l.n.  hn.rl.n.n.i  Morton.. 

j 

1 

H" 

Platid.ia  ■marylandien.  C.  A AT  

•1. 

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1 

Moleuscoidea.  Bryozoa. 

T^isp.nspn.rsn  rni'imis  TTlrndi 

1 

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.. 

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Pet.i.p.ii.l.ipnm.  d i.plintiinin.  (i  A Tf 

.t 

Gavaria  dumosa  Ulricdi 

..1 

..1, 

MARYLAXD  GEOLOGICAL  SURVEY 


79 


LOCAL  DTSTRIBUTIOX 


GENERAL  DISTRIBUTION. 


Nanjemoy  Formation. 


POTAPACO 

STAGE. 


WOODSTOCK 

STAGE. 


MARYLAND 

PROVINCE. 


GULF  PROVINCE. 


( 


SPECIES. 

as 

2 

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2 ’= 
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West  ot  Port  Tobacco. 

East  of  Port  'Pobacco. 

Half  mile  below  (’haptd  Point. 

oc 

0 

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s 

Woodstock.  Zone  15.  1 

One  milo  S.  E.  of  Piscataway.  I 

1 Ravine  north  of  Thrift. 

Charles  Branch,  between  Rosaryvilie 
1 and  Upper  Marlboro. 

Upper  Marlboro  (S.  W.  ot  town). 

Upper  Marlboro  (deei)  cut  on  new 
1 R.  R.). 

1 Hills  Bridge.  1 

1 La  1‘lata. 

Woodstock.  Zones  16  and  L. 

Two  miles  above  Popes  (n-eek. 

1 1)^  miles  above  Popes  Creek.  | 

Popes  Creek. 

Deep  well  at  Chesapeake  Beach  (90- 
93  feet). 

1 Piscataway  stage. 

1 Paspotansa  stage. 

1 Potapaco  stage.  | 

Woodstock  stage.  I 

1 Cretaceous. 

1 Midwayan. 

Lower  Chickasawan. 

1 Upper  Chickasawan. 

1 Lower  Claibornian. 

upper  Claibornian. 

Jacksonian.  | 

1 Post-Eocene. 

Mollusca.  Pelecypoda.-  Co»D‘?med. 

1 

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Molluscoidea.  Brachiopoda. 
Tp.rp.hrn.tii.ln,  hrt.rlnni  Morton  

i 

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Moi-luscoidea.  Bryozoa. 
Discosparsci  varians  Ulrich 

1 

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1 

^ Harris:  Bull.  Amer.  Pal.,  No.  4.  2 jjarris:  Bull.  Araer.  Pal.,  No.  9.  ■‘Aldrich:  Coastal  Plain,  Alabama. 

® Harris:  Proc.  Acad.  N.  Sci.,  Phila.,  1895.  « Dali : Trans.  Wag.  Free  Inst.,  vol.  iii,  pt.  iv. 


80 


THE  EOCENE  DEPOSITS  OF  MAEYLAND 


LOCAL  DISTRIBUTION. 


Aquia  Formation. 


PISCATAWAY  STAGE. 


PASPOTANSA  STAGE. 


SPECIES. 


Molluscoidea.  Bryozoa— Continued. 

Ceriopora  micropora  Goldf 

Heteropora?  tecta  Ulrich 

Memhranipora  rimulata  Ulrich  

Memhranipora  spiculosa  Ulrich 

Membranipora  angusta  Ulrich 

Reptoflustrella  heteropora  G.  & H 

Bijlustra  torta  G.  & H 

Eschara  ? digitata  Morton 

LunuHtes  reversa  Ulrich 

Cribrilina  modesta  Ulrich . 

Cribrilina  crassula'U\riGh  ...  

Lepralia  subplana  T'lrich 

Lepralia  labiosa  Ulrich  

Mucronella  a^pera  Ulrich 

COELENTERATA. 

Flabellum  sp 

Turbinolia  acuticostata  Vaughan 

TrocJiocyathUH  clarkeanus  Vaughan 

Paracyathus  marylandicus  Vaughan  — 
Bala nophy Ilia  desmophyllum  M-E  & H. . . 
Eupsammia  elaborata  (Conrad) 

Protozoa. 

Textularia  gramen  d’Orbigny 

Textularia  sagittula  Defrance 

Textularia  subangulata  d’Orbigny 

Spiroplecta  clarki  Bagg 

Nodosaria  afflnis  (d’Orbigny)  

Nodosaria  bacillum  Defrance 

Nodosaria  communis  (d’Orbigny) 

Nodosaria  consorbrina  v.emaciata(Renss) 

Nodosaria  sandbergeri  (Reuss) 

Nodosaria  obliqua  (Linn6) 

Vaginulina  legumen  (Linne) ... 

Marginula  costata  (Batsck) 

Cristellaria  gibba  d’Orbigny 

Cristellaria  rotatula  ( Lamarck) 

Cristellaria  radiata  (Bornemann) 

Polymorphina  austriaca  (d’Orbigny) 

Polymorphina  communis  d’Orbigny 

Polymorphina  compressa  d’Orbigny 

Polymorphina  elegantissima  P.  & J 

Polymorphina  gibba  d’Orbigny 

Polymorphina  lactea  (W.  & J.) 

Polymorphina  praelonga  Terq 

Olobigerina  bulloides  d’Orbigny 

Discorbina  bertheloti  (d’Orbigny) 

Discorbina  turbo  (d'Orbigny)  

Truncatulina  lobatula  (W.  & J.) 

Truncatulina  ungeriana  (d’Orbigny) 

Anomalina  ammonoides  (Reuss) 

Anomalina  grosserugosa  (Gumbeli 

Pulvinulina  exigua  var.  obtusa  Bur 

Pulvinulina  schreibersii  (d’Orbigny)  . . . 

Nonionina  afflnis  Reuss 

Amphistegina  lessonii  d’Orbigny 

Plantae. 

Carpolithus  marylandicus  Hollick 

Carpolithus  marylandicus  var.  rugosus  H. 


1 Fort  Washington.  I 

1 Seat  Pleasant  (Railroad  cut).  I 

1 Brooks  estate,  near  Seat  Pleasant. 

1 Piscataway  Creek.  1 

1 Swan  Creek,  near  Piscataway.  I 

1 Glymont.  | 

1 Aquia  Creek.  1 

Liverpool  Point.  I 

1 Reedy  Run.  I 

1 Clifton  Beach.  | 

Wades  Bay. 

1 Leeland.  | 

1 Three  miles  west  of  Leeland.  I 

1 Collington.  I 

One  mile  N.  E.  of  Grimesville.  I 

Three  miles  W.  of  Pisgah.  I 

Winchester.  I 

Fredericktown,  Cecil  Co.  I 

One  mile  N.  E.  of  Piscataway. 

Tinkers  Creek,  near  Piscataway. 

Pomonkey  Neck. 

One  mile  S.  E.  of  Mason  Springs. 

Potomac  Creek. 

Two  miles  below  Potomac  Creek. 

Paspotansa  Creek. 

Mattawoman  Creek. 

Upper  Marlboro. 

Hardesty.  | 

One  mile  west  of  Hardesty. 

Between  Buena  Vista  and  Collington. 

Crownsville. 

Two  miles  south  of  South  River.  I 

South  River  (mouth,  of  Broad  Creek).  I 

South  River  (Sheckels  farm).  I 

Annapolis. 

Severn  River. 

Rolphs  Landing. 

Harrisons  Landing. 

Southeast  Creek.  I 

* 

* 

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* 

MAEYLAXD  GEOLOGICAL  SUKVEY 


81 


SPECIES. 

LOCAL  DISTRIBUTION. 

GENERAL  DISTRIBUTION. 

Nanjemoy  Formation. 

POTAPACO 

STAGE. 

? 

WOODSTOCK 

STAGE. 

MARYDAND 

PROVINCE. 

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Molluscoidea.  Bryozoa..— Continued. 

* 

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* 

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TTlr.ir»Vi 

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i^riDriti  jia  ^ ^ ^ ... 

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^ 7/^  ^ jp  /7  7"T'l  */^Vi 

.*. 

COELENTERATA. 

Flabellum  sp 

* 

* 

• 

Turbinolia  acuticostata  Vaughan 

Trochocyathus  clarkeanus  Vaughan 

1 

Paracyathus  marylandicus  Vaughan 

Balanophyllia  desmophyllum  M-E  & H... 

8 

:*=« 

Eupsammia  elaborata  (Conrad) 

* 

Protozoa. 

Textularia  gramen  d’Orbigny 

1 

L. 

Textularia  sagtttula  Defrance 

Textularia  subangulata  d’Orbigny 

* 

Spiroplecta  clarki  Bagg 

* 

* 

Nodosaria  afflnis  (d’Orbigny) 

Nodosaria  bacilluni  Defrance 

* 

Nodosaria  communis  (d’Orbigny) 

Nodosaria  consorbrina  v.emaciata  ( Reuss) 
Nodosaria  sandbergeri  (Reuss) 

Nodosaria  obliqua  (Linne> 

’1 

Vaginulina  legumen  (Linne) 

* 

Marginula  costata  Batsch 

1 

Oristellaria  gibba  d’Orbigny 

Cristellaria  rotatula  (Lamarck) 

1 

Cristellaria  radiata  (Bornemann) 

1 

♦ 

Polymorphina  austriaca  (d’Orbigny) 

.. 

1 

Polymorphina  communis  d’Orbigoy 

..1 

■ ■ 

* 

Polymorphina  compressa  d’Orbigny 

• •1 

• •1 

Polymorphina  elegantissima  P.  & j 

Polymorphina  gibba  d’Orbigny 

• • 

* 

1 

Polymorphina  lactea  (W.  & j.) 

‘i 

Polymorphina  praelonga  Terq 

! 

• 

* 

Globigerina  bulloides  d’Orbigny 

* 

Discorbina  bertheloti  (d’Orbigny) 

Discorbina  turbo  (d’Orbigny) 

Truncatulina  lobatula  (W.  & j.) 

1 

* 

1 

I 

Truncatulina  unaeriana  (d’Orhie-nv) 

* 

* 

Anomalina  ammonoides  (Reuss) 

Anomalina  grosserugosa  (Giimbeli  i .. 

Pulvinulina  exigua  var.  obtusa  Bur .. 

Pulvinulina  schreibersii  (d’Orbigny)  .. 

* 

* 

Nonionina  afflnis  Reuss .. 

Amphistegina  lessonii  d’Orbigny ..' 

1 

Plantae. 

Carpolithus  marylandicus  Hollick 

1 

* 

Carpolithus  marylandicus  var.  rugosus  H.  . . 

® Vaughan : Mono,  xxxix,  U.  S.  G.  S.  Cretaceous  of  N.  J.,”  Ulrich,  see  p.  2iii.  “ Maastricht,”  Ulrich,  see  p.  310. 
6 


82 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


Correlation  of  Deposits. 

Numerous  attempts  have  been  made  to  correlate  the  Eocene  deposits 
of  Maryland  with  those  of  other  areas.  Not  only  has  the  attempt  been 
made  to  establish  the  equivalency  between  the  Maryland  deposits  and 
those  of  adjoining  states  to  the  north  and  south,  but  also  with  the  more 
distant  Gulf  region  and  with  Europe.  That  the  conclusions  reached  by 
the  various  investigators  have  been  widely  at  variance  has  already  been 
shown  in  the  Historical  Eeview,  Some  have  considered  the  strata  to 
represent  but  a small  part  of  the  full  Eocene  series,  while  others  have 
regarded  them  to  embrace  a considerable  portion  of  the  same.  These 
diverse  views  will  be  discussed  in  detail  in  the  subsequent  pages. 

Two  methods  of  correlation  are  possible,  one  based  upon  physical,  the 
other  upon  biological  criteria.  The  faunal  and  floral  characteristics  of 
the  formations  find,  therefore,  interpretation  only  as  the  physical  fea- 
tures are  clearly  understood  since  the  geological  and  geographical  range 
of  species  is  determined  to  a large  extent  by  conditions  of  sedimentation. 
The  physical  characteristics  of  a formation,  therefore,  bear  a close 
relationship  to  its  contained  faunas,  and  cannot  be  ignored  in  the  corre- 
lation of  the  deposits. 

It  is  a well-recognized  fact  thut  the  most  trustworthy  correlations  are 
those  based  upon  paleontological  criteria,  still  the  possibilities  of  varia- 
tion in  the  succession  of  organic  forms  in  widely  separated  areas  are 
so  great  that  detailed  correlation  can  seldom  be  satisfactorily  attempted 
even  where  general  equivalence  is  recognized.  This  is  particularly 
true  of  the  Eocene  of  the  Middle  Atlantic  Slope  where,  as  will  be 
shown  later,  the  range  of  species  is  quite  different  in  certain  particu- 
lars from  that  hitherto  recognized  in  adjacent  provinces.  Such  being 
the  case,  it  is  evident  that  whatever  aid  the  physical  criteria  can  afford 
should  be  employed  in  the  interpretation  of  the  Maryland  Eocene  de- 
posits. 

correlation  of  the  deposits  within  the  MIDDLE  ATLANTIC  SLOPE. 

It  has  generally  been  conceded  that  the  Maryland  and  Virginia 
Eocene  deposits  constitute  one  and  the  same  geologic  province,  a con- 
clusion which  is  well  borne  out  by  the  fact  that  the  strata  are  practically 
continuous  and  that  the  materials  of  the  deposits  and  the  fossils  are 


MARYLAND  GEOLOGICAL  SURVEY" 


83 


freqiientl}'  the  same.  It  is  evident,  however,  that  the  Maryland  beds 
especially  form  the  lower  horizons,  while  the  Virginia  deposits  repre- 
sent more  largely  the  upper  horizons  of  the  Pamunkey  group.  In 
other  words,  the  Aquia  formation  is  more  strongly  developed  in  Maryland 
and  the  I^anjemoy  formation  more  strongl}^  in  Virginia,  although  the 
Xanjemoy  formation  is  by  no  means  lacking  in  Maryland  and  the  same 
is  true  of  the  Aquia  formation  in  Virginia.  It  is  apparent  that  there 
must  have  been  a gradual  transgression  of  the  Eocene  deposits  south- 
ward, since  the  Aquia  formation  gradually  disappears  under  the  IsTanje- 
moy  to  the  south  of  the  Potomac;  on  the  other  hand,  the  E’anjemoy 
formation  is  entirely  absent  to  the  northeast  of  the  Patuxent  valley, 
while  the  Miocene  deposits  have  gradually  transgressed  over  the  Eocene 
from  the  Potomac  valley  northward,  so  that  successively  older  horizons 
are  found  in  contact  with  the  Miocene  in  passing  from  the  Potomac 
basin  northeastward  toward  Delaware,  where  the  Miocene  strata  ulti- 
mately come  to  rest  directly  on  the  Cretaceous  deposits.  The  result  of 
this  ditferential  movement  is  to  limit  the  area  of  outcrop  of  the  Nanjemoy 
formation  in  Maryland  to  the  southern  counties  of  the  state,  while  the 
Aquia  formation  is  continued  across  the  Chesapeake  Bay  into  the  eastern 
counties  as  well  and  finally  disappears  beneath  the  Miocene  cover  not 
far  from  the  borders  of  Delaware.  It  is  evident,  therefore,  that  higher 
Eocene  horizons  are  found  in  central  and  southern  Virginia  than  appear 
in  Maryland,  a conclusion  borne  out  by  the  fact  that  the  Ostrea  sellae- 
formis  zone  with  its  accompanying  fossils  is  much  more  strongly  repre- 
sented in  the  valleys  of  the  Pamunkey  ,and  James  rivers  than  in  the  Po- 
tomac basin.  Thick  beds  of  Ostrea  sellaefor7nis  are  found  in  the  former 
areas,  while  only  a few  representatives  of  this  species  appear  in  the  upper 
zone  of  the  Woodstock  substage  on  the  banks  of  the  Potomac. 

CORRELATION  OF  THE  DEPOSITS  WITH  THE  EOCENE  FORMATIONS  OF  THE 
GULF  STATES. 

By  common  consent  the  extensive  and  diversified  series  of  Eocene 
deposits  found  in  the  Gulf  region  has  come  to  be  regarded  as  the  type  not 
only  for  the  Atlantic  Coast  region  but  for  the  entire  country  as  well. 
Dr.  Dali,  basing  his  conclusions  both  on  his  own  work  and  on  that  of 
others  in  this  area,  has  recently  adopted  the  following  classification  of 


84 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


American  Eocene  horizons.  The  sequence  of  stages  from  above  down- 
wards as  given  by  him  is  as  follows: 

Jacksonian, 

Claihornian, 

Chickasawan, 

Midwayan. 

Paleontological  Criteria. 

A comparison  of  the  Maryland  Eocene  faunas  with  those  represented 
in  the  Gulf  area,  which  have  primarily  afforded  the  basis  for  the  classi- 
fication above  given,  shows  that  the  Maryland  Atlantic  Coast  Eocene 
contains  a great  many  species  not  represented  in  the  Gulf,  or  of  which 
the  exact  range  there  has  not  been  well  enough  determined  for  com- 
parison (158  out  of  207),  while  the  majority  of  identical  forms  (49  in 
all)  are  of  wide  geological  range,  and  are  thus  of  little  value  in  deter- 
mining the  exact  age  of  the  deposits.  There  are  enough  distinctive 
species,  however,  as  will  be  seen  from  a study  of  the  table,  to  show 
that  the  Maryland  Eocene  must  represent  beyond  any  doubt  the 
Chickasawan  with  both  its  upper  and  lower  substages,^  and  that  from 
the  Potomac  basin  southward  through  Virginia  we  also  have  in  all 
probability  the  Lower  Claibornian  as  well,  with  its  Osirea  sellaeformis 
zone. 

Whether  higher  or  lower  stages  of  the  Eocene  are  represented  in  the 
Middle  Atlantic  Slope  is  a question  that  cannot  be  satisfactorily  an- 
swered. There  are  no  paleontological  data  that  bear  on  this  point,  and 
the  other  evidence  which  may  be  brought  forward  cannot  be  regarded  as 
conclusive.  The  non-fossiliferous  zone  at  the  base  of  the  Aquia  forma- 
tion may  or  may  not  be  older  than  the  Chickasawan,  and  the  highest 
strata  recognized  as  Eocene  in  central  and  southern  Virginia  have  not 
been  sufficiently  studied  to  show  whether  they  are  or  are  not  younger 
than  the  lower  Claibornian. 

The  following  table  contains  the  forms  common  to  the  Maryland  and 
Gulf  areas: 

1 TheUpper  Chickasawa^i  used  includes  the  Hatchetigbee  and  Woods  Bluff  (or 

Bashi)  substages,  while  the  Lower  Chickasmoan  includes  the  Bells  Landing  (or  Tusca- 
homa),  Greggs  Landing  and  Nanafalia  substages  as  differentiated  in  Alabama  and 
Mississippi. 


MARYLAND  GEOLOGICAL  SURVEY, 


EOCENE,  PLATE  VIII, 


FtG.  1.— CONTACT  OF  NANJFJMOY  AND  AQUIA  FORMATION,S  IN  VALLEY  OF  I'.EARD 
CREEK,  ANNE  ARUNDEL  COUNTY. 


Fig.  2.— CONTACT  OF  NANJEMOY  AND  AQUIA  FORMATION.S  AT  UFl’ER  MARLRORO. 


VIEWS  OF  EOCENE  SECTIONS. 


MARYLAND  GEOLOGICAL  SURVEY 


85 


Tornatellam  hella  Conrad 

Pleurotorna  childveni  Lea 

Cancellaria  (jraciloides  Aldrich  yar. 

VolutUitheH  petrosiis  (Conrad) 

Caricelhi  pyr uloides  (Conrad) 

Fastis  sahtennis  Tleilprin 

Fastis  inter  str  hit  as  Tleilprin 

Trophon  suhlevis  Harris 

Levifasas  trabeatus  Conrad.... 

Chrysodotnas  euyonatas  (Heilprin). 

Pyrula  penita  var  Conrad 

Fusoficala  jiwenis  (Whitfield).  . 

Jforio  breindentata  (Aldrich).  . . 

Cypraea  siaithi  Aldrich 

Valyptraphoras  triuodiferiis  Conrad. 

Turritella  mortoni  Conrad 

Tarritella  humerosa  Conrad.  ... 

Afesalia  obrata  (Conrad) 

Lanatia  marylandica  Conrad.  . 

(\ilyptraea  uperta  (Solander) -/r 

Odostomia  trapaqaara  (Harris) 

Fiso  ambilicaia  (Lea) 

('adalas  abraptas  Meyer  and  Aldrich -:f 

Corbala  sabengonata  Dali 

CorbnJa  aldrichi  Meyer 

Corbala  oniscns  Conrad 

Meretrix.  ovata  Conrad 

Meretrix  siibhnpressa  (Conrad) 

Dosiniopsis  lettHcula^'is  {RogeTS>) 

Lucina  aqaiana  Clark -x- 

Lucina  astartif ormis  Aldrich 

Lucina  nhleri  Clark -x 

Venericardia  plardcosta  var.  regia'^  Conra*' 

Modiolus  alabamensis  Aldrich 

Pecten  dalli  Clark -x- 

Pecten  choctarensis  Aldrich * 

Pecten  johnsoni  Clark 

Ostrea  cornpressirostra  Say  ....  -x- 

Ostrea  sellaef ormis  Conrad 

Ostrea  (Oryphaeostrea)  vomer  (.Morton)  . . . -x- 

Pteria  lirnala  (Conrad) -x- 

C’hyvymeris  idoaens  (Conrad; -x- 

Trigoitoarca  decisa  (Conrad) 

Oacallaea  gigantea  Conrad 

Ltda  parva  (Rogers) 

Leda  potomacensis  Clark  and  Martin  

Xacula  ovula  I^ea 


Balanopbyllia  desmophyllurn  andH..  

Eapsauimia  el aborata  {Convitd) 


’ The  V.  planieosta  of  the  Middle  Atlantic  Slope  has  been  divided  by  the  authors  of 
this  paper  into  several  species,  the  var.  regia  being  limited  to  the  Aquia  stage.  The 
other  species  have  not  been  recognized  in  the  Gulf  region,  although  further  investi- 
gation may  show  one  or  more  of  them  to  exist  there. 


86 


THE  EOCENE  DEPOSITS  OF  MARYLAND 


In  the  above  table  and  in  the  following  discussion  only  the  mollusca 
and  corals  are  included.  Many  of  the  other  species  occur  outside  of  the 
state^  hut  they  are  not  considered  here  because  the  facts  at  hand  are  not 
complete  enough  to  base  upon  them  any  generalizations  concerning  the 
distribution  of  the  forms  or  any  deductions  concerning  their  significance. 

Aquia  Stage. — The  Aquia  stage  includes  the  following  species  that 
have  been  found  in  the  Lower  Chickasawan  of  the  Gulf^  several  of 
which,  as  will  he  seen  by  the  table,  also  range  downward  into  the  Mid- 
way an,  while  others  pass  upward  into  the  Upper  Chickasawan  and  even 
into  the  Claibornian.  Some  of  these  forms  also,  as  will  he  further  seen 
from  an  examination  of  the  table,  are  not  confined  alone  to  the  Aquia, 
but  range  on  into  the  Nanjemoy  stage.  The  following  Lower  Chick- 
asawan species  are  found  in  the  Aquia: 


Tornatellaea  hella  Conrad. 
rieurotoma  childreni  Lea. 

CJancellaria  graciloides  Aldricli. 
Volutilithes  petrosus  (Conrad). 
(Jaricella  pyruloides  (Conrad). 

Fnsus  s^ibtenuis  Heilprin. 

Trophon  sziblevis  Harris. 
Chrysodormts  engonatus  (Heilprin). 
Fasoficula  juveuis  ( WLitfleld). 

Morio  hrevedentala  (Aldrich). 
Calyptraphorus  trinodiferus  Conrad. 
Turritella  mortoni  Conrad. 
Turritella  humerosa  Conrad. 

Lunatia  WMrylandica  Conrad. 
f'ahyptraea  aperta  (Solander). 

A^<,so  umMlicata  (Lea). 


(?)  Odo8tomia  trapaquara^  (Harris). 
Cadulus  abruptus  Meyer  and  Aldrich. 
Corbula  subengonata  Dali. 

Corbula  aldrichi  Meyer. 

Meretrix  ovata  Conrad. 

Fosiniopsis  lenticularis  (Rogers). 

Lucina  aqniana  Clark. 

Pecten  johnsoni  Clark. 

Ostrea  compressirostra  Say. 

Giycymeris  idoneus  (Conrad). 

Cuctdlaea  gigantea  Conrad. 

Leda  parva  (Rogers). 

Nttcula  ovula  Lea. 

Balanophyllia  desmophylbna  M-E.  and  H. 
Enpsammia  elaborata  (Conrad). 


Of  these  forms  a few  only  are  restricted  to  the  Lower  Chickasawan, 
the  remainder  ranging  on  into  the  Upper  Chickasawan  and  some  on  into 
the  Claibornian  as  well.  The  restricted  forms  are: 

Trophon  stiblevis  Harris.  Lucina  aquiana  Clark. 

Morio  brevidentata  (Aldrich).  CucuUaea  gigantea  Conrad. 

Dosiniopsis  lenticular'is  (Rogers). 


All  of  these  species,  except  CucuUaea  gigantea,  are  confined  to  the 
Aquia  stage. 

' See  the  discussion  of  this  form  in  the  chapter  on  Systematic  Paleontology,  p.  156. 


MAEYLAXD  GEOLOGICAL  SUEVEY^ 


87 


The  following  species  of  the  Aqiiia  stage,  on  the  other  hand,  have 'not 
been  found  below  the  Upper  Chickasawan,  viz.: 

F^cshs  biter striatus  Heilpriu.  Pecteu  choctavensis  Aldrich. 

Lucina  uhleri  Clark.  Pterici  lininla  (Conrad). 

Modiolus  alabame?isis  Aldrich. 

Of  these,  Pteria  limula  also  occurs  in  the  Claihornian.  The  Aquia 
stage  also  contains  several  species  that  have  not  been  found  below  the 
Claihornian  in  the  Gulf.  They  are: 

31esalia  obruta  (Conrad).  Corbula  onisctis  Conrad. 

{?)  Odostomia  trapaquara  (Harris). 

The  following  species  occur  in  the  Jacksonian,  viz.: 

Cadulus  abruptus  Meyer  and  Aldrich.  Pecten  dalli  Clark. 

Corbula  oniscus  Conrad.  Ostrea  {Gyphaeostrea)  vomer  (Morton). 

None  of  them  is  of  special  significance. 

Before  final  conclusions  are  drawn  from  these  comparisons,  however, 
the  fact  must  he  taken  into  consideration  that  the  Maryland  beds  have 
probably  been  examined  at  the  present  time  more  thoroughly  and  at  a 
greater  number  of  localities  within  the  same  limited  area  than  those  of 
the  Gulf,  and  that  some  of  the  forms  above  mentioned  may  be  shown 
upon  further  study  to  have  a wider  range  in  the  Gulf  than  has  been 
given  to  them.  Due  allowance  must  also  he  made  for  differences  in  judg- 
ment in  the  identification  of  species.  At  the  same  time,  it  is  very  clear 
that  the  species  common  to  the  Gulf  and  Middle  Atlantic  Slope  differ 
materially  in  their  geological  range.  This  is  evidently  due  in  part  to 
the  difference  in  physical  conditions  in  the  two  areas  and  also  in  part 
to  migration.  But  after  taking  these  facts  into  consideration  it  will 
be  seen  that  the  fauna  of  the  iVquia  is  much  more  closely  related  to  the 
Chickasawan  as  a whole  than  to  either  the  Midwayan  or  Claihornian  and 
that  there  is  a somew^hat  closer  resemblance  to  the  Lower  than  to  the 
Upper  Chickasawan.  The  distance,  however,  between  the  two  areas, 
the  difference  in  physical  conditions  and  the  possibilities  of  migration 
are  too  great  to  admit  of  any  attempt  to  draw  exact  parallelism  between 
the  substages. 

Nanjemoy  Stage. — The  Nanjemoy  stage  contains  the  following  species 
found  in  the  Lower  Chickasawan  of  the  Gulf,  all  but  one  of  which 
{Cucullaea  gigantea)  also  range  on  upward  into  the  Tapper  Chickasawan 
or  higher  stages.  They  are: 


THE  EOCENE  DEPOSITS  OF  MAKYLAND 


Tornatellaea  hella  Conrad. 

Volntilithes  petrosus  (Conrad). 
Levifusus  trabeatus  Conrad. 

Cypraea  smithi  Aldrich. 
Calyptraphorus  trinodifertis  Conrad. 
Lunatia  marylandica  Conrad. 
Calyptraea  aperta  (Solander). 

Cadulus  abruptus  Meyer  and  Aldrich. 


Corbula  subengonata  Dali. 
Corbula  aldrichi  Meyer. 
Meretrix  ovata  (Conrad.) 
Pecteu  jolmmni  Clark. 
Glycymeris  idoneus  (Conradh 
Cucullaea  glga'ntea  Conrad. 
Leda  parva  (Rogers). 


The  Nanjemoy  stage  contains  the  following  species  found  in  the  Upper 
Chickasawan  of  the  Gulf.  They  are: 


Tornatellaea  bella  Conrad. 

Volutilithes  petrosas  (Conrad). 

Fusas  interstriatus  Heilprin. 

Levifusus  trabeatus  Conrad. 

Cypraea  smithi  Aldrich. 
Calyptraphorus  trinodif erus  Conrad. 
Lunatia  m,arylandica  Conrad. 
Calyptraea  aperta  (Solander). 

Cadulus  abruptus  Meyer  and  Aldrich. 
C)  Corbula  subengonata  Dali. 

Corbula  aldrichi  Meyer. 

Meretrix  ovata  Conrad. 

Among  these  species  a few  only 
asawan.  They  are: 

Fusus  interstriatus  Heilprin. 

Meretrix  subimpressa  Conrad. 

Lucina  astartif ortnis  Aldrich. 

Lucina  uhleri  Clark. 


Mey'etrix  subimpressa  Conrad. 

Lucina  astartiformis  Aldrich. 

Lucina  uhleri  Clark. 

2Lodiolus  alaLamensis  Aldrich. 

Fecten  choctavensis  Aldrich. 

{?)  Fecten  johnsoni  Clark. 

(.^)  Ostrea  sellaef oymiis  Conrad. 

Fteria  limula  (Conrad). 

Glycymeris  idoneus  (Conrad). 
Trigonoarca  decisa  (Conrad). 

Leda  parva  (Rogers). 

Leda  potomacensis  Clark  and  Martin. 

are  restricted  to  the  Upper  Chick- 

Modiolus  alabamensis  Aldrich. 

Fecten  choctavensis  Aldrich. 

Leda  potomacensis  Clark  and  Martin. 


Of  these  forms  Meretrix  subimpressa,  Lucina  astartiformis  and  Leda 
potomacensis  are  found  only  in  the  Nanjemoy  stage. 

The  following  species  of  the  Uanjemoy  stage  are  found  in  the  Lower 
Claihornian: 


Volutilithes  petrosus  (Conrad). 
Levifusus  trabeatus  Conrad. 

Fyrula  penita  var  Conrad. 

Mesalia  obruta  (Conrad). 

Lmmatia  marylandica  Conrad. 
Calyptraea  aperta  (Solander). 

Cadulus  abruptus  Meyer  and  Aldrich. 


G)  Corbula  subengonata  Dali. 
Corbula  aldrichi  Meyer. 

Corbula  oniscus  Conrad. 

Ostrea  sellaeformis  Conrad. 
Fteria  limula  (Conrad). 

O Glycymeris  idoneus  (Conrad). 
Trigonoarca  decisa  (Conrad). 


Among  these  forms  Mesalia  obruta  is  the  only  species  that  is  confined 
to  the  Lower  Claihornian,  while  three  others  do  not  pass  the  limits  of 
the  Claihornian  stage,  viz.,  Pyrula  penita  var.,  Corbula  oniscus  and  (?) 
Ostrea  sellaeformis. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  IX. 


Fra.  1.— POPES  CREEK  BLUFF  SHOWING  ZONE  OVERLAIN  BY  MIOCENE 
DIATOMACEOUS  EARTH. 


Fra.  ‘2.-RAILROAD  CUT  NEAR  UPPER  MARLBORO  SHOWING  NANJEMOY  FORMATION 
OVERLAIN  BY  LATER  DEPOSITS. 


VIEWS  OF  EOCENE  SECTIONS. 


MAKYLAND  GEOLOGICAL  SUEVEY 


89 


Of  the  list  above  given,  Levifusus  trdbeatus,  Pyr’ula  penita  var.,  Ostrea 
sellaeformis  and  Trigonoarca  decisa  are  confined  to  the  Nanjemoy  stage. 

The  following  Nanjemoy  species  have  been  found  in  the  Upper  Clai- 
hornian: 

Fi/rula  penita  va7\  Conrstd.  Corbula  oniscus  Conrad, 

Lunatia  mai'ylandica  Conrad.  Ostrea  sellaef oi'mis  Conrad. 

Calyptraea  aperta  (Solander).  Ptei'ia  litnula  (Conrad). 

hTone  of  these  species  are  confined  to  the  Upper  Claibornian  and  two 
of  them  only,  Pyrula  penita  var.  and  Ostrea  sellaeformis,  are  dis- 
tinctively Nanjemoy  forms. 

The  following  species  occur  in  the  Jacksonian,  viz.: 

Cadulus  ab^'uptus  Meyer  and  Aldrich.  Pecte7i  dalli  Clark. 

Co7'bula  07iiscus  Conrad.  Ost7'ea  (Gyphaeost7'ea)  voTner  (Morton). 

Xone  of  them,  however,  has  any  special  significance. 

It  is  thus  shown  that  the  Uanjemoy  has  faunal  relationships  both 
with  the  Chickasawan  (and  especially  with  the  Upper  Chickasawan) 
and  with  the  Lower  Claibornian.  But  in  the  Nanjemoy  the  lack  of  par- 
allelism in  the  succession  of  faunas  between  the  Middle  Atlantic  and 
Gulf  regions  is  even  more  noticeable  than  in  the  lower  beds.  The  only 
conclusion  which  can  be  drawn  is  that  the  Uanjemoy  of  Maryland  rep- 
resents such  portion  of  the  Chickasawan  as  lies  above  that  represented 
by  the  Aquia,  while  the  occurrence  of  the  highly  characteristic  species, 
Ostrea  sellaeformis,  in  the  Uanjemoy  stage  in  Maryland,  although  not 
so  numerously  or  typically  represented  as  in  the  still  higher  strata  in 
central  and  southern  Virginia,  points  to  the  possible  Lower  Claibornian 
age  of  the  highest  beds  of  the  Maryland  Eocene. 

Geological  Criteria. 

The  lithological  and  stratigraphical  characteristics  of  the  Eocene  de- 
posits of  the  Middle  Atlantic  Slope  afford  some  important  criteria  for 
the  correlation  of  the  strata.  In  the  first  place,  the  homogeneous  nature 
of  the  materials,  already  referred  to,  is  a significant  feature,  and  indi- 
cates conditions  undisturbed  by  important  physical  changes  throughout 
the  period  of  Eocene  deposition.  Again,  the  fact  that  the  strata  are  so 
largely  composed  of  secondary  materials  sliows  that  the  position  of 
accumulation  was  in  the  vicinity  of  a coast  reached  by  no  large  sediment- 


90 


THE  EOCEXE  DEPOSITS  OF  MARYLAND 


bearing  rivers,  while  at  the  same  time,  for  the  most  part,  sufficiently 
removed  from  the  coast-line  to  be  iinaifected  by  shore  conditions.  It  is 
further  evident  that  these  deposits,  which  are  so  largely  glauconitic,  were 
very  slowly  accumulated,  as  has  been  shown  in  the  case  of  the  formation 
of  greensand  upon  the  beds  of  existing  seas. 

When  we  compare  these  conditions  of  accumulation  on  the  Middle 
Atlantic  Slope  with  the  conditions  that  prevailed  in  the  Gulf  region 
during  Eocene  time  marked  differences  appear.  In  the  latter  area 
numerous  rivers,  draining  the  interior  of  the  continent,  discharged  large 
quantities  of  material  throughout  much  of  the  Eocene,  making  the 
deposits  highly  diversified.  Instead  of  the  greensands  and  greenish  and 
black  clays  of  the  Middle  Atlantic  Slope,  which  no  longer  to  any  great 
extent  characterize  the  strata,  are  found  coarser  beds  of  sand  and  clay, 
often  partly  calcareous,  which  give  every  indication  of  more  rapid 
accumulation.  To  compare,  therefore,  the  200  to  300  feet  of  green- 
sands and  clays  of  the  Middle  Atlantic  Slope  with  one  or  two  subdi- 
visions of  hardly  equal  thickness  in  the  Gulf  region  would  scarcely  be 
attempted,  even  upon  geological  grounds.  The  strata  of  the  Middle 
Atlantic  Slope  must  be  represented  in  the  Gulf  by  deposits  many  times 
their  thickness. 

The  State  Geological  Survey  of  Alabama  has  estimated  the  total 
thickness  of  the  Eocene  beneath  the  Jacksonian  at  1500  feet,  600  feet 
of  this  belonging  to  the  Chickasawan  and  450  feet  to  the  Claibornian. 
The  Lower  Chickasawan  is  given  a thickness  of  about  350  feet  and  the 
Upper  Chickasawan  a thickness  of  about  250  feet,  the  Bells  Landing 
division  of  the  former  having  a thickness  of  less  than  150  feet.  The 
paleontological  evidence  previously  cited,  combined  with  the  geological 
data  here  presented,  show  the  far  greater  thickness  of  the  geologically 
contemporaneous  deposits  in  the  Gulf  as  compared  with  those  of  the 
Middle  Atlantic  States. 

Furthermore  the  general  relations  of  the  strata,  occurring  as  they  do 
between  the  Cretaceous  and  Neocene  along  both  the  Atlantic  and  the 
Gulf  coasts,  give  some  indication  of  the  continental  movements  to  which 
each  province  was  subjected.  Although  the  movements  may  not  have 
been  absolutely  contemporaneous,  they  nevertheless  afford  satisfactory 


MAllYLAXD  GEOLOGICAL  SURVEY 


91 


criteria  for  the  broad  correlation  of  the  deposits,  their  more  exact  par- 
allelism being  determined  on  other  and  more  definite  grounds. 

European  Equivalents. 

Several  attempts  have  been  made  to  correlate  the  deposits  of  the 
Middle  Atlantic  Slope  with  those  of  Europe.  The  earlier  attempts  in 
this  direction  are  presented  in  the  Historical  Eeview.  Most  of  the  con- 
clusions reached  were  based  on  very  insufficient  data,  the  faunas  being 
inadequately  studied  and  even  the  sequence  of  deposits  not  being  in 
most  instances  fully  understood;  but  even  after  Conrad"  began  his  study 
of  the  Maryland  Tertiaries  and  described  more  or  less  fully  the  rich 
faunas  contained  therein,  his  correlations  were  still  based  on  very  insuf- 
ficient knowledge.  As  the  result  of  his  investigations,  he  correlated 
the  Eocene  deposits  of  Mainland  with  the  London  Clay  of  England  and 
the  Calcaire  Grassier  of  France. 

Lyell,''  during  his  visit  to  America  in  1841,  examined  somewhat  hur- 
riedly the  Eocene  deposits  of  the  Middle  Atlantic  area,  but  attempted  no 
detailed  correlation,  stating,  however,  that  the  Tertiary  formations  whicli 
he  saw  agree  well  in  their  geological  types  with  the  Eocene  and 
Miocene  beds  in  England  and  France.^^ 

Heilprin,"*  in  an  important  publication  on  United  States  Tertiary 
Geology,  discusses  the  equivalency  of  the  European  and  American  Ter- 
tiary formations.  In  a chapter  dealing  with  A Comparison  of  the 
Tertiary  Mollusca  of  the  Southeastern  United  States  and  Western  Europe 
in  Eelation  to  the  Determination  of  Identical  Forms,^^  he  refers  to  the 
species  which  Conrad,  Lea  and  Meyer  had  regarded  as  analogous  to  Euro- 
pean forms,  and  also  discusses  in  detail  all  those  species  which  he  regards 
as  the  same  or  which  have  certain  points  of  resemblance.  Eeferring  to 
the  more  important  of  these  forms  in  an  earlier  portion  of  the  same 
volume  (p.  13)  he  says:  “If  such  comparisons  are  of  any  value  strati- 

graphically,  we  may  fairly  look  upon  the  Maryland  Eocene  deposits — the 

’Jour.  Acad.  Nat.  Sci.  Phila.,  voL  vi,  ISJO,  pp.  205-217;  Fossil  Shells  of  the 
Tertiary,  1882,  pp.  iv,  0,  12,  18. 

•■’Proc.  Geol.  Soc.  London,  vol.  iv,  1845,  pp.  568-564;  Quart.  Jour.  Geol.  Soc.  London, 
vol.  i,  184.5,  p.  429-430. 

’’ Contribiitions  to  the  Tertiary  Geology  and  Paleontology  of  the  United  States, 

pp.  88-101. 


THE  EOCENE  DEPOSITS  OE  MARYLAND 


\}2 


Piscataway  sands  below,  and  tlie  Marlborougii  rock  above — as  represent- 
ing a horizon  nearly  equal  to  that  of  the  Thanet  sands  of  England  and 
the  Bracheux  sands  of  the  Paris  basin,  or  of  the  British  Bognor  rock 
(London  clay).  Tn  either  case  they  would  be  near  the  base  of  the  Eocene 
series.'^ 

Dr.  Dali/  in  a recent  article  on  ‘‘A  Table  of  the  North  American 
Tertiary  Horizons,  Correlated  with  one  Another  and  with  Those  of 
^Yestern  Europe,  with  Annotations,’^  correlates  the  Maryland  formations 
with  the  Suessonian  of  Europe.  As  the  writers  of  this  report  believe, 
however,  that  the  Eocene  of  Maryland  represents  more  than  the  lower 
Chickasawan  of  tlie  Gulf,  they  would  assign  to  the  Maryland  Eocene  a 
somewhat  wider  range  in  the  European  Eocene.  It  seems  highly 
probable  that  the  Londonian  and  even  the  Parisian  in  part  are  also 
represented.  The  few  identical  species  in  the  two  areas  have  a wide  range 
geologically,  and  are  thus  of  little  value  for  purposes  of  detailed  corre- 
lation. Other  species  may  ultimately  be  found  in  common,  but  more 
careful  comparisons  than  have  been  made  will  be  necessary  to  estab- 
lish this  fact.  Until  such  investigations  have  been  made  the  correlation 
of  the  deposits  on  the  two  sides  of  the  Atlantic  can  he  at  best  only 
provisional. 


' 18th  Aun.  Kept.  U.  S.  Geol,  Survey,  pt.  ii,  1898,  pp.  327-348. 


SYSTEMATIC  PALEONTOLOGY 


EOCENE 


EEPTILIA  B.  C.  Case. 

PISCES  Charles  E.  Eastman. 

AETHEOPODA  E.  0.  Ulrich. 

MOLLUSCA W.  B.  Clark  and  G.  C.  Martin. 

MOLLUSCOIDEA. 

BEACmOPODA W.  B.  Clark  and  G.  C.  Martin. 

BEYOZOA  E.  0 Ulrich. 

COELENTEEATA T.  Wayland  Vaughan. 

ECHIUODEEMATA W.  B.  Clark  and  G.  C.  Martin. 

PEOTOZOA  E.  M.  Bagg,  Jr. 


PLAYTAE 


Arthur  Rollick. 


VERTEBRATA. 

Class  REPTILIA. 

Order  CROCODILIA. 

Suborder  ENSUCHIA. 

Family  CROCODILIDAE. 

Genus  THECACHAMPSA  (CROCODILUS)  Cope. 

Thecachampsa  sp. 

Plate  X,  Pigs.  1,  2. 

Description. — A very  large  vertebra,  probably  dorsal,  gives  evidence  of 
an  animal  of  considerable  size.  The  anterior  face  is  deeply  concave, 
and  the  rounded  posterior  face  marked  by  a deep  pit.  It  is  impossible 
to  determine  whether  the  vertebra  belongs  to  any  one  of  the  species 
below  described  and  which  are  based  on  the  teeth  and  jaws  alone,  and  it 
therefore  seems  undesirable  to  assign  a specific  name  to  it. 

Occurrence. — Aquia  Foematiox.  Liverpool  Point. 

Collection. — Maryland  Geological  Survey. 

Thecachampsa  sekicodox  (?)  Cope. 

Plate  X,  Fig.  3. 

Thecachampsa  sericodon  Cope,  1867.  Proc.  Acad.  Nat.  Sci.  Phila.,  p.  143. 

Thecachampsa  sericodon  Cope,  1869.  Proc.  Acad.  Nat.  Sci.  Phila.,  p.  12  ; Amer. 
Nat.,  p.  91. 

Thecachampsa  sericodon  Cope,  1871.  Trans.  Amer.  Phil.  Soc.,  vol.  xlv,  p.  64,  pi.  v, 
figs.  7 and  8.  (Pages  1-104  appeared  in  1869.) 

Thecachampsa  sericodon  Cope,  187-t.  Proc.  Acad.  Nat.  Sci.  Phila.,  p.  363. 

Description. — A long  slender  tooth  with  a strong  root  represents  this 
or  an  allied  species.  The  specimen  is  water-worn  and  it  is  impossible 
to  determine  its  characters  exactly. 

Occurrence. — Aquia  Foematiox.  Clifton  Beach. 

Collection. — Maryland  Geological  Survey. 


96 


SYSTEMATIC  PALEONTOLOGY 


Thecachampsa  contusor  Cope. 

Plate  Fig.  4. 

Thecachampsa  contusor  Cope,  1867.  Proc.  Acad.  Nat.  Sci.,  Phila.,  p.  143. 

Description. — This  species  was  recognized  by  Cope  as  of  doubtful 
value  and  he  considered  the  forms  placed  here  as  possibly  belonging  to 
T.  antiqua.  A specimen  in  the  collection  has  the  characters  assigned 
to  contusor  except  that  the  section  of  the  base  is  elliptical  instead  of 
rounded,  and  certainly  does  not  belong  to  antiqua,  so  that  it  may  be 
placed  here  provisionally. 

Occurrence. — Aquia  Formation.  Aquia  Creek. 

Collection. — Maryland  Geological  Survey. 

Thecachampsa  marylandica  Clark. 

Plate  X,  Fig.  5. 

Thecachampsa  marylandica  Clark,  1895.  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Thecachampsa  marylandica  Clark,  1896.  Bull.  141,  U.  S.  Geol.  Survey  p.  58,  pi. 
vii,  fig.  1. 

Description. — The  specimen  is  a fragment  of  the  jaw,  described  as 

moderately  thick,  the  single  complete  and  one  partially  preserved 
alveoli  not  far  removed  from  one  another.  Teeth  with  elongate, 
slightly  curved,  conic  crowns;  basis  circular,  its  diameter  about  one- 
third  the  length  of  the  tooth;  apex  acute,  circular;  surface  with  fine 
prolongations  and  striations.^’  Clark,  1895. 

Dimension  of  the  tooth  38  mm.,  diameter  at  base  12  mm. 

Occurrence. — Aquia  Formation.  Clifton  Beach,  Upper  Marlboro. 

Collections. — Johns  Flopkins  University,  Maryland  Geological  Survey. 

COPROLITE. 

Plate  X,  Fig.  6. 

Coprolite  Clark,  1895.  Bull.  141,  U.  S.  Geol.  Survey,  p.  60,  pi.  vii,  fig.  4. 

Description. — A reptilian  coprolite  of  very  perfect  form.  It  is  only 
one-half  preserved.  These  coprolites  are  rather  common  in  the  forma- 
tion. 

Occurrence. — Aquia  Formation.  Clifton  Beach. 

Collection. — Johns  Hopkins  University. 


MARYLAND  GEOLOGICAL  SURVEY 


or 


Order  TESTUDENATA. 

Suborder  CRYPTODIRA. 

Family  CHELONIIDAE. 

Genus  EUCLASTES  Cope. 

Euclastes  (?)  sp.  Clark. 

Plate  X,  Fig.  7. 

Euclastes  {?)  sp.  Clark,  189.5.  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  No.  4. 

Euclastes  {?)  sp.  Clark,  1896.  Bull.  141,  U.  S.  Geol.  Survey,  p.  59. 

Description. — Several  fragments  from  the  carapace  of  a large  sea 
turtle  were  found  at  Clifton  Beach,  but  they  were  not  sufficiently  well 
preserved  to  identify  the  genus  with  certainty.  Fragments  of  the  costals 
show  that  the  surface  was  smooth  and  the  edges  of  the  plate  more  or 
less  rounded.  The  shields  were  relatively  thin.’^  Clark,  1895. 

Occurrence. — Aquia  Formation.  Clifton  Beach. 

Collectio7i. — Johns  Hopkins  University. 


Suborder  TRIONYCHIA. 

Family  TRIONYCHIDAE. 

Genus  TRIONYX  Geoffroy. 

Trionyx  virginiana  Clark. 

Plate  XI,  Figs.  1,  2. 

Trioyiyx  virginiana  Clark,  1895.  Johns  Hopkins  Univ.  Circ.,  vol.  xv.  No.  4. 

Trionyx  virginiana  Clark,  1896.  Bull.  141,  U.  S.  Geol.  Survey,  p.  59,  pi.  viii,  fig'S. 
la  and  lb. 

Description. — Fragments  of  costals  with  tuberculated  and  ridged  sur- 
faces, characteristic  of  the  genus  Trionyx.  The  longitudinal  ridges  are 
prominent,  at  times  irregular  and  inosculate;  relatively  remote  and 
separated  by  intervals  of  about  twice  their  width;  generally  entirely 
disappear  near  the  margins  of  the  plates. 

Length  of  the  largest  fragment  130  mm.,  width  45  mm.,  thickness 
18  mm. 


98 


SYSTEMATIC  PALEONTOLOGY 


This  fragment  is  evidently  one  of  the  terminal  costals  with  no  pro- 
jecting portion  of  the  rib  beyond  the  plate. 

Occurrence. — Aquia  Fokmation.  Aqnia  Creek. 

Collections. — Wagner  Free  Institute  of  Science,  Johns  Hopkins  Uni- 
versity, Maryland  Geological  Survey. 


Class  PISCES. 

Order  ELASMOBRANCH 1 1. 

Suborder  TECTOSPONDYLI. 

Family  MYLIOBATIDAE. 

Genus  MYLIOBATIS  Cuvier. 

The  following  remarks  on  the  crushing  pavement-teeth  of  the  great 
Eagle-rays,^^  so  abundant  in  the  American  and  European  Eocene,  are 
extracted  from  an  important  paper  on  sharks’  teeth  from  the  English 
Eocene  by  A.  S.  Woodward."" 

The  dentition  of  each  jaw  in  this  genus  [Myliodatis']  comprises 
large,  flattened,  hexagonal  teeth,  arranged  in  seven  antero-posterior 
series.  In  very  young  individuals,  the  teeth  are  all  approximately  of 
equal  size,  hut  quite  early  in  life  the  median  teeth  begin  to  become  rela- 
tively very  broad,  and  as  the  animal  grows,  this  disproportion  of  the 
median  teeth  gradually  becomes  greater  and  greater.  When  unworn 
or  unahraded,  the  grinding  surface  of  the  teeth  is  covered  with  a thin 
enamel-like  layer  of  gano-dentine,  usually  marked  with  antero-pos- 
teriorly  directed  striations;  hut  when  this  layer  is  removed,  the  tooth 
has  a punctate  appearance,  owing  to  the  exposure  of  the  vertical  nutri- 
tive canals  traversing  the  underlying  vascular  dentine.  In  naming  the 
fossils,  it  is  thus  necessary  to  take  into  account  the  size  of  the  specimen, 
and  remember  that  the  surface  markings  depend  on  the  state  of  preser- 
vation. It  is  also  necessary  to  note  that  the  dental  plate  of  the  lower 
jaw  is  flat,  while  that  of  the  upper  jaw  curves  round  the  supporting 
cartilage.” 


Proc.  Geol.  Assoc.,  vol.  xvi,  1899,  p.  3. 


MAEYLAND  GEOLOGICAL  SURVEY 


99 


Myliobatis  copeanus  Clark. 

Plate  XII,  Figs.  1,  2;  Plate  XIII,  Figs.  2a,  2b,  G,  7a,  7b. 

Myliobatis  copeamcs  Clark,  1805.  Johns  Hopkins  Univ,  Circ.,  vol.  xv,  p.  4. 

Myliobatis  copea7ttis  Clark,  1896.  Bull.  141,  U.  S.  Geol.  Survey,  p.  61,  pi.  vii,  figs. 

3a,  36. 

Description. — Dentition  large  and  massive,  the  coronal  contour 
strongly  curved  antero-posteriorly,  and  moderately  arched  from  side  to 
side  in  the  upper  jaw,  but  only  very  slightly  so  in  the  lower.  Trans- 
verse sutures  strongly  and  regularly  concave  toward  the  front  in  upper 
median  teeth,  less  so  in  those  of  lower  jaw,  where  they  are  sometimes 
slightly  serrated.  Upper  median  teeth  relatively  longer  than  the  lower, 
but  often  variable  in  this  respect;  as  a rule  they  are  about  five  times  as 
broad  as  they  are  long  in  the  adult.  Lateral  teeth  long  and  narrow, 
arranged  parallel  with  the  main  axis.  Surface  smooth  and  polished 
when  unabraded,  but  becoming  longitudinally  striated  and  fissured 
when  worn.  Oral  surface  of  lower  dental  plate  exhibiting  a slight 
longitudinal  depression  along  the  central  portion,  and  under  surface  cor- 
respondingly thickened,  the  latter  having  an  arcuate  contour  from  side 
to  side. 

This  species  is  very  abundant  in  the  Eocene  of  Maryland  and  Vir- 
ginia, but  is  apparently  unknown  beyond  the  limits  of  these  states.  A 
large  series  of  specimens  has  been  collected,  thus  facilitating  a compari- 
son of  successive  growth  stages,  and  of  variations  due  to  wear  and  other 
causes.  It  is  a remarkably  massive  form,  the  thickness  of  the  median 
teeth  equalling  that  of  if.  pachyodon  from  the  Miocene,  and  the  trans- 
verse section  being  very  much  the  same.  In  the  latter  species,  how- 
ever, the  transverse  sutures  of  the  median  teeth  are  nearly  straight, 
being  only  slightly  curved  backward  at  the  extremities,  whereas  the 
present  form  is  distinguished  by  the  median  sutures  being  uniformly 
concave  toward  the  front.  The  curvature  of  the  suture-lines  is  usually 
more  pronounced  in  the  upper  dentition  than  in  the  lower,  and  in  the 
newe.st-formed  teeth  than  in  those  more  anteriorly  situated.  The  me- 
dian teeth  of  the  lower  dental  plate  are  also  somewhat  shorter,  as  a rule, 
than  those  in  the  upper  jaw,  and  the  coronal  contour  is  much  less  arched 
from  side  to  side. 


100 


SYSTEMATIC  PALEONTOLOGY 


Dental  pavements  are  not  uncommon  showing  as  many  as  nine  longi- 
tudinal series  of  median  teeth  intact  (Plate  XIII,  Figs.  6,  7).  One  of 
the  largest  upper  dental  plates  examined  is  from  the  Aquia  Formation 
of  Potomac  Creek,  and  in  this  the  median  teeth  are  6.5  cm.  wide,  1.5  cm. 
long,  and  3 cm.  thick,  not  including  the  root.  The  antero-posterior 
curvature  of  the  coronal  surface  is  so  great  as  to  form  a nearly  perfect 
semicircle,  having  a diameter  of  8 cm.  and  a periphery  of  over  12  cm. 
Nine  of  the  median  teeth  are  preserved  in  regular  series,  together  with 
a portion  of  the  lateral  series  on  both  sides.  There  is  considerable  re- 
semblance between  this  species  and  M.  liolmesii  from  the  Eocene  of 
South  Carolina. 

The  type  consists  of  fragmentary  dental  plates  of  the  upper  and  lower 
jaws. 

Occuirence. — Xanjemoy  Formation.  Woodstock.  Aquia  Forma- 
tion. Clifton  Beach,  Liverpool  Point,  Aquia  Creek,  Potomac  Creek. 

Collectio7is. — Johns  Hopkins  ITnivcrsity,  Maryland  Geological  Survey. 

Myliobatis  magister  Leidyi 
Plate  XII,  Fig.  3;  Plate  XIII,  Figs,  la,  lb. 

Jfyllobatis  magister  Leidy,  1876.  Proc.  Acad.  Nat.  Sci.  Phila.,  p.  86. 

Myliobatis  magister  Laidy^  1877.  Jour.  Acad.  Nat.  Sci.  Phila.,  N.  S.,  vol.  viii,  p. 

283,  pi.  xxxiii,  tig.  7. 

Myliobatis  Iwlmesii  Woodward,  1890.  Cat.  Foss.  Fishes,  Brit.  Mus.,  pt.  i,  p.  122. 

Description. — Dentition  very  large  and  massive,  the  median  teeth  at 
least  six  times  wider  than  long,  their  sutures  curved  backward  near  the 
lateral  margins,  and  sometimes  very  faintly  so  in  the  central  area. 
Coronal  contour  of  upper  dental  plate  uniformly  arched  from  side  to 
side,  and  also  to  an  equal  extent  in  a longitudinal  direction;  lower  dental 
plate  less  curved  antero-posteriorly  than'  the  upper,  and  slightly  de- 
pressed along  the  median  line.  Surface  smooth  when  unworn,  or  with 
fine  superficial  striae  slightly  convergent  toward  the  front. 

This  gigantic  species,  ■which  is  exceeded  in  size  only  by  the  Egyptian 
M.  peutoni,  is  not  actually  known  to  occur  in  Maryland,  being  confined, 
so  far  as  known,  to  the  Eocene  Phosphate  Beds  of  South  Carolina.  It 
is  noticed  in  this  connection,  however,  because  of  the  interest  attached 


MAEYLAXD  GEOLOGICAL  SUKVEY 


101 


to  the  original^  which  is  the  largest  specimen  hitherto  reported  from 
this  country.  The  figured  specimen  was  found  at  Ashley,  South  Caro- 
lina, and  is  preserved  in  the  Mnsenm  of  Comparative  Zoology  at  Cam- 
hridge,  Massachusetts.  The  strong  curvature  of  the  oral  surface,  which 
is  equal  in  both  longitudinal  and  transverse  directions,  together  with 
the  proportions  and  wavy  sutures  of  the  median  teeth  prove  it  beyond 
all  doubt  to  he  the  upper  dentition,  previously  unknown,  of  a species 
founded  by  Leidy  on  a unique  lower  dental  plate  from  the  same  locality, 
to  which  he  applied  the  name  M.  magister.  Leidy  himself,  and  follow- 
ing him  A.  S.  Woodward,  were  of  the  opinion  that  the  type-specimen 
might  represent  the  lower  dentition  of  M.  Iwlmesii  Gihhes,  which  was 
described  from  a supposed  upper  dental  plate  with  strongly  curved  su- 
tures. The  specimen  in  the  Cambridge  collection,  however,  completes 
our  knowledge  of  the  dentition  of  ill.  magister,  and  we  must  look  else- 
where for  the  opposing  dentition  of  Gihhes’  species.  The  latter,  as  has 
already  been  intimated,  appears  to  he  only  very  slightly  different  from 
J/.  copeamis  of  this  state. 

The  type  consists  of  a lower  dental  plate. 

Collections. — Philadelphia  Academy  of  Natural  Sciences,  Museum  of 
Comparative  Zoology,  Cambridge. 

Genus  AETOBATIS  Muller  and  Henle. 

In  this  genus  there  is  hut  a single  series  of  very  broad,  flat  teeth, 
those  of  the  upper  jaw  only  differing  from  the  median  teeth  of  Mylio- 
hatis  in  their  truncated  lateral  ends.  The  lower  dentition  is  very  nearly 
flat,  and  the  teeth  are  all  more  or  less  strongly  curved  or  angularly  bent 
in  the  middle.  The  coronal  surface  is  smooth  or  slightly  striated,  and 
the  attached  surface  of  the  root  longitudinally  ridged  or  grooved. 
Woodward^  remarks  that  “In  this  genus  there  is  much  less  variability 
in  the  relations  of  the  length  and  breadth  of  the  teeth  according  to  age 
than  in  Myliolatis ; but  the  form  of  the  lower  teeth  is  so  inconstant, 
that  species  cannot  be  determined  upon  the  evidence  of  the  lower  denti- 
tion alone.” 


' Cat.  Foss.  Fishes^  British  Mmeum,  pt.  i,  1889,  p.  138. 


102 


SYSTEMATIC  PALEONTOLOGY 


Aetobatis  aecuatus  Agassiz. 

Plate  XIII,  Figs.  3a,  3b,  8. 

Aetohatis  arcuains  Agassiz,  1843.  Poiss.  Foss.,  vol.  iii,  p.  337. 

Aetohat'h  arcnatuti  Cope,  1867.  Proc.  Acad.  Nat.  Sci.  Pbila.,  p.  139. 

Aetobatis  profundus  Cope,  1867.  Loc.  cit.y  p.  139. 

Aetohatis  arcuatns  Leidy,  1877.  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  ser.,  vol.  viii,  p. 

245,  pi.  xxxi,  tigs.  14-18. 

Aetobatis  prof  undus  Leidy,  1877.  Loc.  cit..,  p.  346,  pi.  xxxi,  tigs.  19,  20. 

Descriptio7i. — This  species  is  known  only  by  fragments  belonging 
chiefly  to  the  lower  dentition,  and  consequently  cannot  be  accurately 
deflned.  Founded  originally  on  detached  teeth  from  the  Miocene  of 
Switzerland,  it  has  been  recognized  by  Cope  and  Leidy  from  the  corre- 
sponding horizon  in  Maryland,  but  has  not  been  hitherto  reported  from 
the  Eocene.  It  would  appear  to  be  very  rare  in  the  latter  formation, 
as  only  a few  detached  teeth  have  been  collected  by  the  Maryland  Geo- 
logical Survey.  A number  of  Miocene  forms  from  Charles  county  are 
flgnred  by  Leidy  (loc.  cit.,  1877,  pi.  xxxi),  Avho  very  plausibly  suggests 
that  the  narrow  rounded  crowns  described  by  Cope  as  A.  profundus  are 
in  reality  only  worn  anterior  teeth  belonging  to  the  species  under  con- 
sideration. Other  species  of  Aetohatis  occur  in  the  Eocene  of  Xew  Jer- 
sey and  South  Carolina. 

Occurrence. — Xanjemoy  Formation.  Popes  Creek.  Aquia  Forma- 
tion. Aquia  Creek. 

Collection. — Maryland  Geological  Survey. 

Suborder  ASTEROSPONDYLl. 

Family  CESTRACIONTIDAE. 

Genus  SYNECHODUS  Woodward. 

This  genus  of  Cestraciont  sharks  is  known  by  the  nearly  complete 
dentition  and  parts  of  the  skeleton  in  the  Lias  of  England,  vdiere  it 
accompanies  such  allied  forms  as  Hyhodus,  Acrodus,  etc.,  and  detached 
teeth  have  also  been  described  from  the  Cretaceo-Tertiary  of  Xew  Zea- 
land. Its  remains  have  not  been  heretofore  reported,  however,  from 
strata  of  undoubted  Tertiar}-  age,  and  the  following  species  ma}"  be  re- 
garded as  the  latest  survivor  of  the  genus  of  which  we  have  any  record. 


MARYLAND  GEOLOGICAL  SURVEY^ 


103 


Sy^nechodus  clarkii  n.  sp. 

Plate  XIV,  Figs.  5a,  5b,  5c. 

Description. — Teeth  of  small  or  moderate  size,  but  of  relatively  stout 
proportions,  and  symmetrical.  Median  cone  sharply  recurved,  gently 
tapering,  smooth,  convex  on  both  faces,  and  cutting  edges  not  conspicu- 
ously defined;  on  either  side,  two  much  smaller  cones,  the  external  one 
being  the  lesser  of  the  two.  Eoot  massive  and  somewhat  turgid,  pro- 
duced in  the  arc  of  a circle  on  the  inner  face,  and  flat  below;  nutrient 
foramen  small. 

The  total  height  of  the  tooth,  oriented  in  its  natural  position,  is  7 mm. 
The  distance  from  apex  to  base  of  crown,  measured  along  its  recurved 
outer  face,  is  6 mm.  The  width  and  thickness  of  the  crown  at  its  base 
are  equal,  amounting  to  3 mm.,  whereas  the  corresponding  measure- 
ments of  the  root,  taken  at  their  maximum,  are  8 mm.  and  4 mm.  re- 
spectively. 

This  unique  tooth  appears  sufficiently  well  characterized,  notwith- 
standing that  the  lateral  cones  are  broken  off  above  the  base,  to  warrant 
recognition  as  a distinct  species,  and  it  may  be  fittingly  named  in  honor 
of  the  State  Geologist.  Much  interest  is  attached  to  the  fact  of  its 
coming  from  a Tertiary  horizon. 

Occurrence. — Aquia  Formation.  Liverpool  Point. 

Collection. — Maryland  Geological  Survey. 

Family  LAMNIDAE. 

Genus  ODONTASPIS  Agassiz. 

The  teeth  of  this  genus  are  very  similar  to  those  of  the  Cretaceous 
Scapanorhynchus,  a survivor  of  which  has  been  recognized  in  Mitsiku- 
rina  of  the  present  day;  and  they  are  also,  as  remarked  by  Agassiz,  very 
difficult  to  distinguish  from  those  of  Lanina.  The  crown  is  high,  nar- 
row and  compressed  in  all  except  a few  hindermost  teeth,  and  adjacent 
to  it  are  one  or  two  pairs  of  lateral  denticles,  generally  sharply  pointed. 
The  anterior  teeth  are  especially  high-crowned,  comparatively  large  and. 
slender,  with  a much  produced  bifurcated  root. 


104 


SYSTEMATIC  TALEONTOLOGY 


Odontaspis  elegans  (Agassiz). 

Plate  XIV,  Figs.  2a,  2b,  2c,  3a,  3b,  3c. 

Lamna  elegans  Agassiz,  1843.  Poiss.  Foss.,  vol.  iii,  p.  369,  pi.  xl6,  fig.  24. 

Lamna  elegans  Gibbes,  1849.  Jour.  Acad.  Nat.  Sci.  Pbila.,  2nd  ser.,  vol.  i,  p.  196, 
pi.  XXV,  figs.  98-102  (?  figs.  96,  97). 

Lamna  elegans  Emmons,  1858.  Kept.  Geol.  Surv.  N.  Car.,  p.  239,  figs.  70,  71. 

Lamna  elegans  Noetling,  1885.  Abb.  Geol.  Spenialk.  Preussen  u.  Thiiring.  Staaten, 
vol.  vi,  pt.  3,  p.  61,  pi.  iv. 

Odontaspis  elegans  Woodward,  1889.  Cat.  Foss.  Fishes,  British  Mus.,  pt.  i,  p.  361. 

Odontaspis  elegans  Clark,  1895.  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Odontaspis  elegans  Clark,  1896.  Bull.  141,  U.  S.  Geol.-  Surve}’,  p.  62. 

Odontaspis  elegans  Woodward,  1899.  Proc.  Geol.  Assoc.,  vol.  xvi,  p.  8,  pi.  i,  figs. 
15-18. 

Description. — Anterior  teeth  with  a very  high  and  narrow  crown,  only 
slightly  curved,  the  inner  face  strongly  striated  longitudinally,  and 
scarcely  flattened  in  the  middle.  A single  pair  of  small,  prickle-like 
lateral  denticles,  and  nutritive  foramen  on  the  prominent  inner  side  of 
the  root  placed  in  a deep  cleft.  Lateral  teeth  with  an  almost  equally 
slender,  but  less  elevated  crown,  which  is  similarly  striated  and  flanked 
with  relatively  large,  slender  denticles.  The  two  branches  of  the  root 
are  long,  compressed  and  generally  pointed. 

This  is  the  most  abundant  of  all  Eocene  sharks’  teeth  in  Maryland 
and  Virginia,  but  is  of  rare  occurrence  in  the  Miocene.  It  is  a some- 
what smaller  form  than  0.  macrota,  and  tlie  anterior  teeth  of  the  two 
species  are  so  much  alike  that  it  is  ditficnlt  to  separate  them.  This  is 
especially  true  of  worn  specimens  (Plate  XIV,  Fig.  2)  where  the  den- 
ticles are  wanting  and  the  striation  of  the  inner  face  inconspicnons,"  and 
chief  reliance  must  be  placed  on  the  narrowness  of  the  crown.  The 
anterior  teeth  sometimes  exceed  4 cm.  in  total  height.  Dr.  F.  Xoetling, 
and  following  him,  Jaekel  and  Smith  Woodward,  have  been  chiefly  in- 
strumental in  reconstructing  the  dentition  of  this  and  other  species  of 
Odontaspis. 

The  type  consists  of  teeth  and  associated  vertebrae  in  the  museum  of 
College  of  Surgeons,  London. 

Occurrence. — Aquia  Formation.  Aquia  Creek,  Fort  Washington, 
Liverpool  Point. 

Collections. — Jolms  Hopkins  Fniversit}',  Maryland  Geological  Survey. 

1 On  the  striation  of  Selachian  teeth,  see  J.  Probst,  Wurtt.,  Jahresb.,  vol.  xv, 
1859,  p.  100. 


3IARYLAXD  GEOLOGICAL  SURVEY 


105 


Odoxtaspis  macrota  (Agassiz). 

Plate  XI Y,  Figs.  4a,  4b. 

Otodus  macrotiis  Ao-assiz,  184o.  Poiss.  Foss.,  vol.  iii,  p.  273,  pi.  xxxii,  figs.  29-31. 
Lamna  elegans  Agassiz,  1843.  Tom.  cit..,  p.  289,  pi.  xxv,  figs.  1-7  ; pi.  xxxviia, 
figs.  58,  59. 

Lamna  compressa  Agassiz,  1843.  Tom.  cit.,  p.  290,  pi.  xxxviia,  figs.  35-42. 

Lamna  compream  Gibbes,  1849.  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  ser.,  vol.  i, 
p.  197,  pi.  xxv,  figs.  107-112. 

Otodus  mac  rot  us  Gibbes,  1849.  Tom.  cit.,  p.  200,  pi.  xxvi,  figs.  2,  143,  144. 

I^amna  compressa  Emmons,  1858.  Kept.  Geol.  Surv.  N.  Car.,  p.  240,  figs.  72,  75,  7(5. 
Odontaspis  rnacrota  O.  Jaekel,  1895.  Mem.  Comite  Geol.,  St.  Petersb.,  vol.  ix,  pp. 
11,  29,  pi.  i,  figs.  8-17. 

Odontaspis  rnacrota  Woodward,  1899.  Proc.  Geol.  Assoc.,  vol.  xvi,  p.  9,  pi.  i,  figs. 
19,  20. 

Description. — Anterior  teeth  much  compressed,  the  inner  face  with 
fainter,  more  wavy  and  more  interrupted  strioe  than  those  of  0.  elegans. 
Typical  lateral  teeth  much  compressed,  croivn  with  sharp  cutting  edges 
and  a faintly  striated  inner  face;  outer  coronal  face  gently  convex.  A 
single  pair  of  large  and  broad  lateral  denticles,  iisnally  rounded,  but 
sometimes  obtusely  pointed. 

This  species  is  tolerably  abundant  in  the  Eocene  of  various  localities 
in  Maryland  and  Virginia,  especially  at  Liverpool  Point  on  the  Potomac 
river.  The  lateral  teeth  rarely  exceed  2.5  cm.  nor  the  anterior  3.5  cm. 
in  total  height. 

Occurrence. — Xaxjemoy^  Formatiox.  Woodstock.  Aquia  Forma- 
Tiox.  Aqnia  Creek,  Fort  AYashington,  Liverpool  Point. 

Collection. — Maryland  Geological  Survey. 

Odoxtaspis  cuspid ata  (Agassiz). 

Plate  XIY",  Figs,  la,  lb,  Ga,  Gb. 

Lamna  cuspidata  Agassiz,  1843.  Poiss.  Foss.,  vol.  iii,  p.  290,  pi.  xxxviia,  figs. 
43-50. 

lAirnna  cuspidata  Gibbes,  1849.  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  ser.,  vol.  i,  p.  197, 
pi.  xxv,  figs.  103-10(5. 

Lamna  clavata  Agassiz,  1856.  Kept.  Pac.  R.  R.  Explor.  and  Surv.,  vol.  v,  p.  310, 
pi.  i,  figs.  19-21. 

Tjumna  clavata  Agassiz,  1850.  Amer.  Jour.  Sci.,  ser.  ii,  vol.  xxi,  p.  275. 

Odontaspis  hopei  Noetling,  1885.  Abb.  Geol.  Specialk.,  Preussen  u.  Thiiring, 
Staaten,  vol.  vi,  pt.  3,  p.  71,  pi.  v,  figs.  1-3. 

Odontaspis  cuspidata  Woodward,  1899.  Proc.  Geol.  Assoc.,  vol.  xvi,  p.  7,  pi.  i, 
figs.  12-14. 


106 


SYSTEMATIC  PALEONTOLOGY 


Description. — Teeth  scarcely  distinguishable  from  those  of  0.  elegans 
except  by  their  slightly  smaller  size  and  by  the  absence  of  striae  upon 
the  inner  coronal  face.  Anterior  teeth  much  elevated  and  narrow,  hut 
moderately  stont.  Lateral  denticles  of  both  anterior  and  lateral  teeth 
occasionally  flanked  by  a smaller  secondary  pair. 

Teeth  belonging  to  this  species  accompany  those  of  0.  elegans  and 
0.  macrota  in  various  localities  of  Maryland  and  Virginia,  but  are  less 
numerous  than  either  of  these  forms.  From  the  Miocene  of  this  state, 
very  few  examples  have  been  obtained.  In  some  specimens  two  well- 
developed  pairs  of  lateral  denticles  occur,  as  shown  in  Plate  XIV,  Fig.  1, 
and  also  in  Figs.  86a  and  87a  of  Emmoifls  Xorth  Carolina  Geological 
Survey  Eeport  (1858),  p.  241. 

Occurrence. — Xanjemoy  Formation.  Popes  Creek,  Woodstock. 
Aquia  Formation.  Mattawoman  Creek,  Fort  Washington,  Liverpool 
Point. 

Collection. — Maryland  Geological  Survey. 

Genus  OTODUS  Agassiz. 

Nearly  all  the  species  assigned  by  Agassiz  to  this  genus  have  been 
distributed  by  subsequent  authors  among  Lamna,  Odontaspis  and 
Oxyrhina.  Noetling  even  goes  so  far  as  to  refer  the  type-species 
0.  obliquus,  to  the  genus  C arcliarodon,  although  the  coronal  margin  is 
never  distinctly  serrated.  The  best  modern  opinion  is  that  the  pecu- 
liarly robust  teeth  belonging  to  this  species  should  be  provisionally  re- 
tained in  the  place  provided  for  it  by  its  founder,  and  along  with  this 
should  be  ranged  a second,  somewhat  smaller  species  occurring  in  Eng- 
land and  Eussia,  known  as  0.  trigonalis  (Jaekel). 

Otodus  obliquus  Agassiz. 

Plate  XV,  Figs.  l-4c. 

Otodus  obliqmts  Agassiz,  1843,  Poiss.  Foss.,  vol.  iii,  p.  267,  pi.  xxxi,  pi.  xxxvi, 
figs.  22-37. 

Otodus  obliquus  Gibbes,  1849.  Jour.  Acad.  Nat.  Sci.  Pliila.,  3ud  ser.,  vol.  i,  p.  199, 
pi.  xxvi,  figs.  131-137. 

Lamna  acuminata  Gibbes,  1849.  Loc.  cit.,  p.  197,  pi.  xxv,  figs.  113,  114  (?  not  fig. 
115). 

Lamna  {?)  obliqua  Clark,  1895.  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Lamna  {?)  obliqua  Clark,  1896.  Bull.  141,  U.  S.  Geol.  Survey,  61. 

Otodus  obliquus  Woodward,  1899.  Proc.  Geol.  Assoc.,  vol.  xvi,  p.  10. 


MARYLAND  GEOLOGICAL  SURVEY 


107 


Description. — Teeth  robust,  attaining  to  a very  large  size;  crown 
moderately  compressed,  sharply  pointed,  with  one  broad  acuminate  pair 
of  lateral  denticles,  and,  in  the  smaller  teeth,  an  additional  pair  of  more 
slender  denticles.  Outer  coronal  face  flat  or  slightly  convex,  without 
folds;  inner  face  smooth.  Inner  face  of  the  root  prominent,  and  nutri- 
tive foramen  not  sunk  in  a groove.”  Agassiz,  1843. 

These  very  robust  teeth  attain  a large  size,  the  crown  sometimes  meas- 
uring 5 cm.  in  height  (cf.  Plate  XV,  Fig.  4),  but  the  majority  of  speci- 
mens do  not  exceed  3 cm.  in  total  height.  The  anterior  teeth  (Plate 
XV,  Fig.  1)  are  narrow  and  erect,  with  rather  deeply  cleft  root,  and 
frequently  with  only  one  or  no  lateral  denticles;  they  are  sometimes  diffi- 
cidt  to  distinguish  from  the  anterior  teeth  of  Odontaspis  macrota.  The 
lateral  teeth  are  distinguished  by  their  broader,  more  compressed  and 
usually  obliquely  directed  crowns.  The  small  hindermost  teeth  are 
often  extremely  broad-based,  but  here  as  elesewhere  in  the  jaws,  much 
individual  variation  occurs.  It  does  not  appear  possible,  however,  to 
recognize  more  than  a single  species  in  the  American  Tertiaries.  Xu- 
merous  examples  are  found  in  the  Eocene  of  Maryland,  Virginia,  Xew 
Jersey,  and  the  Carolinas. 

Occurrence. — Aquia  Formation.  Liverpool,  Aquia  Creek,  Glymont. 

Collections. — Maryland  Geological  Surve}q  Johns  Hopkins  University. 

Genus  CARCHARODON  Agassiz. 

The  teeth  of  Carcliarodon  attain  enormous  size,  exceeding  those  of  all 
other  Selachian  genera.  They  are  triangular,  usually  erect,  and  re- 
semble those  of  Oxyrliina  and  Otodus  except  that  the  edges  of  the  com- 
pressed crown  are  always  serrated.  Some  species  are  without  lateral 
denticles,  others  have  a single  pair,  serrated  like  the  crown.  The  genus 
enjoyed  V world-wide  distribution  during  the  Eocene  and  Miocene,  and 
was  exceedingly  abundant  in  various  localities  of  both  hemispheres.  In 
the  South  Carolina  Phosphate  Beds  the  teeth  are  so  numerous  as  to  be 
of  no  mean  commercial  importance. 


108 


SYSTEMATIC  PALEONTOLOGY 


Cakcharodon  auriculatus  (Blaiiiville). 

Squalus  auriculatus  Blainville,  1818.  Nouv.  Diet.  cl’Hist.  Nat.,  vol.  xxvii,  p.  884. 

Carcharoclon  acuiidens  Gibbes,  1847.  Proc.  Acad.  Nat.  Sci.  Pliila.,  p.  267. 

Carcharodon  augustideiis  Gibbes,  1848.  Jour.  Acad.  Nat.  Sci.  Pbila.,  2nd  ser.,  vol. 
i,  p.  145,  pi.  XIX,  tigs.  10-18,  pi.  xx,  pi.  xxi,  tigs.  87-38. 

Carcharodon  acuiidens  Gibbes,  1848.  Torn,  cit.^  p.  146,  pi.  xxi,  tigs.  39-41. 

Carcharodon  rectus  Agassiz,  1856.  Kept.  Pac.  R.  K.  Explor.  and  Surv.,  vol.  v,  p. 
816,  pi.  i,  tigs.  89-41. 

Carcharodon  rectus  Agassiz,  1856.  Araer.  Jour.  Sci.,  ser.  ii,  vol.  xxi,  p.  274. 

Carcharodon  crassidens  Emmons,  1858.  Kept.  Geol.  Surv.  N.  Car.,  p.  283,  tig.  59a. 

Carcharodon  contortidens  Emmons,  1858.  Loc.  cit.^  p.  288,  tig.  60. 

Carcharodon  angustidens  Leidy,  1877.  Jour.  Acad.  Nat.  Sci.  Pliila.,  2nd  ser.,  vol. 
viii,  p.  258. 

Carcharodon  angustidens  Noetling,  1885,  Abb.  Geol.  Specialk.,  Preussen  u.  Thiir. 
Staaten,  vol.  vi,  pt.  3,  p.  82,  pi.  vi,  tigs.  1-3. 

Description. — Teeth  robust,  comparatively  narrow,  with  a pair  of 
broad  lateral  denticles;  outer  coronal  face  flat  or  slightly  convex.  Lat- 
eral denticles  especially  large  in  the  lateral  teeth,  which  have  a very 
narrow  oblique  crown.^^  Blainville,  1818. 

This  species  is  apparently  very  rare  in  the  Maryland  Tertiaries,  only 
a single  fragmentary  example  having  been  obtained  from  the  Eocene 
of  Popes  Creek,  and  very  few  from  the  Miocene.  Owing  to  its  imper- 
fection, no  figure  is  given  of  the  Eocene  tooth,  but  it  is  to  be  noted  that 
the  lateral  denticles  are  very  feebly  developed,  so  that  the  reference  to 
this  species  is  not  absolutely  certain. 

Occurrence. — Nanjemoy^  Formation.  Popes  Creek. 

Collection. — Maryland  Geological  Survey. 

Family  CARCHARIIDAE. 

The  teeth  of  this  family  of  man-eating  sharks  are  very  abundant 
in  the  Tertiary  of  all  countries,  and  closely  resemble  those  of  the 
Lamnidae.  They  differ  from  the  latter  ho’wever,  in  their  internal  struc- 
ture, being  holloAv  in  the  center  throughout  life,  and  with  minute  tubules 
radiating  from  the  pulp-cavity  across  the  dentine.  The  teeth  are  so 
much  alike  in  existing  genera  that  vdien  found  in  the  detached  fossil 
condition  it  is  often  impossible  to  separate  them.  For  instance,  the 
upper  teeth  of  llypoprion  are  scarce!}’’  distinguishable  from  those  of 
Galeus,  and  isolated  teeth  of  Galeocerdo  and  Spliyrna  are  difficult  to  dis- 
tinguish from  tliose  of  C archarias.  It  is  rather  surprising  that  the  last- 


MARYLAND  GEOLOGICAL  SURVEY 


109 


named  genus  does  not  appear  to  be  present  in  the  Maryland  Eocene,  and 
the  teeth  of  Galeocerdo  contortiis,  although  very  abundant  in  the  corre- 
sponding horizons  of  Virginia  and  South  Carolina,  are  likewise  wanting 
in  this  state.  Hemipristis  serra  is  another  common  form  in  the  Carolina 
Eocene,  and  also  in  the  Miocene  of  the  Atlantic  Slope  extending  as  far 
north  as  Gay  Head,  Massachusetts,  but  is  apparently  unknown  in  the 
Eocene  of  ^laryland  and  Virginia. 

Genus  GALEOCERDO  Miiller  and  Henle. 

The  teeth  of  this  genus  are  serrated  on  both  margins,  have  the  pos- 
terior edge  deeply  notched,  and  the  apex  more  or  less  sharply  inclined 
backward.  As  already  remarked,  some  species  are  very  difficult  to  dis- 
tinguish from  Carcharias,  and  in  the  case  of  the  teeth  referred  to 
G.  mmor  by  Gibbes,  Emmons  and  Cope,  comparisons  show  that  these 
really  belong  to  species  of  Carcharias. 

Galeocerdo  latidens  Agassiz. 

Plate  XIV,  Eig.  8. 

Galeocerdo  latidens  Ajjassiz,  1843.  Poiss.  Foss.,  vol.  iii,  p.  231,  pi.  xxvi,  figs.  22, 
23  (?  tigs.  20,  21). 

Galeocerdo  latidens  Gibbes,  1849.  Jour.  Acad.  Nat.  Sci.  Pbila.,  2nd  ser.,  vol.  i, 
p.  192,  pi.  XXV,  tig-s.  59-02. 

Description. — Teeth  broad,  mostly  low-crowned,  the  largest  meas- 
uring about  .024  cm.  across  the  base.  Anterior  coronal  margin  only 
slightly  arched,  except  near  the  apex;  apex  above  the  posterior  notch 
small,  narrow;  margin  below  the  posterior  notch  long,  straight  and  much 
inclined;  root  large.  Serrations  of  the  coronal  margin  very  prominent.” 

This  species  is  not  uncommon  in  the  Maryland  Miocene,  but  as  yet 
only  a single  example  has  been  obtained  from  the  Eocene  of  this  state. 
Its  jireservation  is  not  so  good  as  might  be  desired,  and  it  is  rather  under 
the  average  size  attained  by  this  species. 

Occurrence. — Xanjemoy"  Formation.  Moodstock. 

Collection. — Maryland  Geological  Survey. 

Genus  SPHYRNA  Rafinesque. 

The  small  teeth  belonging  to  this  genus  are  similar  in  both  jaws, 
oblique,  with  a slight  posterior  notch,  and  margins  smooth  or  serrated. 
Their  resemblance  to  the  teeth  of  Carcharias  has  already  been  noted. 


110 


SYSTEMATIC  PALEONTOLOGY 


Sphyena  pkisca  Agassiz. 

Plate  XIV,  Figs.  7a,  7b. 

Hphyrna py'isca  Agassiz,  1848.  Poiss.  Foss.,  vol.  iii,  p.  334,  pi.  xxvia,  flgs.  35-50. 

Sphyrna  prisca  Gibbes,  1840.  Jour.  Acad.  Nat.  Sci.  Pbila.,  2nd  ser.,  vol.  i,  p.  104, 
pi.  XXV,  figs.  88-00. 

Lamna  compressa  {pars)  Emmons,  1858.  Kept.  Geol.  Surv.  N.  Car.,  p.  340,  figs. 
70-81. 

{?)  Sphyrna  denticulata  Emmons,  1858.  Loc.  cit.^  p.  341,  fig.  84a. 

Description. — Teeth  small,  broad,  gently  oblique,  often  erect,  with 
finely  serrated  edges. 

This  species  is  very  abundant  in  the  Eocene  of  South  Carolina  and 
Miocene  of  Maryland,  but  only  two  or  three  rather  imperfect  examples 
have  been  obtained  from  the  Eocene  of  this  state.  There  was  also  found 
one  doubtful  tooth,  which  may  possibly  belong  to  a distinct  species. 

Occurretice. — Aquia  Eoemation.  Liverpool  Point. 

Collection. — Maryland  Geological  Survey. 

SELACHIAN  VERTEBRAE. 

Detached  vertebrae  of  the  Asterospondylic  type,  consisting  of  calcified 
cartilage  and  therefore  not  well  adapted  for  preservation,  are  occasionally 
met  with  in  the  Eocene  of  Clifton  Beach  and  a few  other  localities  in 
Maryland  and  A'irginia.  Some  of  the  larger  ones  are  but  slightly  con- 
cave on  both  faces,  and  belong  without  doubt  among  the  Lamnidae, 
possibly  to  Otodus  or  CarcJiarodon.  Detached  vertebrae  of  both  Elas- 
mobranch  and  Teleost  fishes  are  much  more  common  in  the  Miocene 
than  Eocene,  and  represent  a considerable  variety  of  forms.  In  Plate 
XII,  Figs.  7a  and  7&  are  represented  detached  vertebrae  of  an  indeter- 
minate species  of  bony  fishes. 


Subclass  TELEOSTOMl. 
Order  ACTINOPTERYGll. 


Kemains  of  bony  fishes  are  very  rare  in  the  Tertiary  of  the  Middle 
Atlantic  Slope,  and  are  confined  to  detached  vertebrae,  otolites  and  por- 
tions of  the  dentition.  A few  species  founded  on  detached  teeth  from 


MAEYLAXD  GEOLOGICAL  SUEVEY 


111 


the  Eocene  of  South  Carolina  have  been  described  by  Leidy/  and  a 
singular  bone  from  the  same  horizon  supposed  to  belong  to  Platax  is 
figured  by  Gibbes."  Cope  records  in  all  only  one  species  of  Actinoptery- 
gians  from  the  Miocene  of  Maryland  {Spliyraena  speciosa),  and  five 
from  the  same  horizon  in  New  Jersey,  as  follows:  Spliyraena  speciosa, 

S.  siloviana,  Pliasganodus  gentry i,  C tommy odus  irregularis,  and  Pliyllo- 
dus  curvidens.^  The  last-named  genus  is  of  exceptionally  rare  occur- 
rence in  the  American  Tertiary,  being  known  only  by  the  four  detached 
dental  plates  noticed  by  WymaiT  and  l)y  Marsh;"  The  peculiar  teeth  first 
described  by  Leidy  from  the  Cretaceous  of  New  Jersey  under  the  name 
of  Ischyrliiza,  occur  also  in  the  Miocene,  of  Maryland  and  North  Carolina, 
if  we  may  credit  the  statements  of  Cope  and  according  to  this  author 
certain  coalesced  caudal  vertebrae  hypnral  fans  accompanying  the 
Cretaceous  teeth  and  occurring  also  in  the  Eocene  of  Maryland  and 
South  Carolina  should  be  referred  to  this  genus,  which  he  claims  is  re- 
lated to  the  Esocidae.  It  is  much  more  likely,  however,  that  the  Cre- 
taceous fans  belong  to  ProtospJiyraena  or  some  similar  form,  and  that 
the  Tertiary  fans,  which  all  agree  in  having  the  terminal  centrum  at- 
tached, belong  to  one  or  more  species  of  Sword-fishes. 

Genus  XI  PH  IAS  Linnaeus. 

Fragmentary  remains  of  Sword-fishes  have  been  met  with  from  time 
to  time  in  various  Tertiary  horizons,  but  in  most  cases  are  insufficient 
for  accurate  identification.  Detached  rostra  and  hypnral  fans  of  large 
size,  both  probably  belonging  to  Xipliias  or  some  related  genus,  are  not 
uncommon  in  the  Eocene  of  South  Carolina.  A number  of  such  re- 
mains, inclndifig  the  types  of  X.  rohustus  Leidy,  are  preserved  in  the 
Holmes  Collection  belonging  to  the  American  Mnsemn  of  Natural  His- 
tory in  New  York.  Here  also  is  to  be  seen  the  tooth  of  Ischyrliiza  mira 
figured  by  Leidy  in  Holmes’  Post-Pleiocene  Fossils  of  South  Carolina 
(Plate  XXV,  Figs.  3,  4),  which  is  the  most  perfect  specimen  of  that 


’ Jour.  Acad.  Nat.  Sci.  Pbila.,  2nd  ser.,  vol.  viii,  1877,  pp.  254-257,  pi.  xxxiv. 

^ Ibid.,  vol.  i,  1849,  p.  300,  pi.  xlii,  figs.  10-13. 

^Proc.  Amer.  Philos.  Soc.,  vol.  xiv,  1875,  p.  362. 

4 Amer.  Jour.  Sci.,  ser.  ii,  vol.  x,  1850,  p.  234. 
sProc.  Amer.  Assoc.  Adv.  Sci.,  18th  Meet.,  1870,  p.  228. 

•^Vertebrata  Cret.  Form.  West,  Kept.  U.  S.  Geol.  Surv.  Territ.,  vol.  ii,1875,  p.  280. 


112 


SYSTEMATIC  PALEOXTOLOGY 


form  extant.  The  Tertiary  caudal  fans  which  have  been  theoretically 
associated  with  the  teeth  of  Isclujrliiza  by  Cope  and  Clark  are  here  con- 
sidered to  belong  to  typical  Sword-fishes.  The  following  species  is  the 
only  one  known  to  occur  in  Maryland. 

XiPHiAS  (?)  RADIATA  (Clark). 

Plate  XII,  Fig.  8. 

Ischyrhizai?)  racliata  Clark,  189.5,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

IschyrMza  (?)  radiata  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  60,  pi.  vii,  fig. 

2a  (?  non  figs.  26,  2c). 

Description. — Terminal  vertebral  centrum  deeply  concave  in  front  and 
circular  in  cross-section,  its  neural  and  haemal  spines  fused  into  a solid 
fan-shaped  body;  the  anterior  haemal  spine  less  completely  fused  with 
the  next  following  than  are  all  the  rest,  and  even  separated  from  it  near 
the  point  of  attachment  with  the  centrum  by  a small  perforation  passing 
completely  through  the  fan.  [Dentition  and  other  parts  of  the  skeleton 
unknown.] 

This  species  is  established  on  a unique  fan-shaped  body,  the  extreme 
height  of  which  is  3.9  cm.;  hut  some  of  the  South  Carolina  specimens 
exceed  10  cm.  The  latter  also  differ  from  the  Maryland  form  in  having 
the  vertebral  centrum  transversely  elongated  instead  of  circular. 

The  type  is  a hypural  fan  in  the  Museum  of  Johns  Hopkins  Uni- 
versity. 

Occurrence. — Aquia  Formatiox.  Clifton  Beach. 

Collection. — Johns  Hopkins  University. 

Genus  PHYLLODUS  Agassiz. 

The  presence  of  this  interesting  genus  in  North  America  was  first 
made  known  by  Dr.  Jeffries  Wyman,"  who  came  into  possession  of  two 
unique  dental  plates  from  the  Eocene  of  Eichmond,  Virginia.  Eather 
poorly  executed  woodcuts  of  both  specimens  are  given  by  him,  the  more 
perfect  one  being  compared  with  P.  toliapicus  Agassiz,  and  the  other 
declared  to  he  different  from  any  described  species.  This  paper  of  Wy- 
man’s seems  to  have  escaped  general  notice,  and  was  certainly  over- 
looked by  Marsh, when  in  1870  he  claimed  his  P.  elegans  and  P.  curvi- 

1 Amer.  Jour.  Sci.,  ser.  ii,  vol.  x,  18.50,  p.  284. 

2 Proc.  Amer.  Assoc.  Adv.  Sci.,  18th  Meet.,  1870,  p.  228. 


MARYLAND  GEOLOGICAL  SURVEA' 


113 


dens,  likewise  founded  on  unique  dental  plates  from  the  Eocene  and 
Miocene  respectively  of  New  Jersey,  to  he  the  first  indications  of  this 
genus  in  North  America.  Neither  of  the  last  two  species  have  been 
figured,  hut  it  is  probable  from  Marsh’s  brief  description  that  P . elegcins 
is  a young  example  of  P.  toliapicus.  Furthermore,  it  is  practically  cer- 
tain that  neither  of  AYyman’s  specimens  are  referable  to  P.  toliapicus, 
but  each  is  representative  of  a distinct  species.  Whether  their  horizon 
is  Eocene  or  Miocene  was  not  conclusively  determined  by  Wyman, 
although  the  chances  are  in  favor  of  attributing  them  to  the  former. 
Traces  of  this  genus  have  not  as  yet  been  discovered  in  Maryland,  but 
the  following  species  deserves  notice  on  account  of  its  historical  and 
scientific  interest. 

Phyllodus  hipparioxyx  n.  sp. 

Phyllodiui  sp.  aflF.  toliapicus  Wyman,  1850,  Amer.  Jour.  Sci.,  ser.  ii,  vol.  x,  p.  234, 
woodc.  fig:.  9rt. 

Type. — Detached  dental  plate;  formerly  in  Museum  of  Comparative 
Zoology,  Cambridge,  Mass. 

OTOLITES. 

Plate  XII,  Figs.  4-6. 

Fish  otolites,  or  ear-stones,’’  are  found  almost  exclusively  in  the 
detached  condition,  this  being  due  to  the  fact  that  they  are  held  in 
place  during  life  only  by  membranes,  and  hence  readily  fall  out  from 
the  head  and  sink  to  the  bottom  while  the  decomposing  body  of  the  fish 
continues  to  float  on  the  surface,  a prey  to  all  sorts  of  creatures,  or  is 
cast  ashore  by  the  waves.  The  circumstance  of  large  numbers  of  fossil 
fish  skeletons  being  found  in  close  proximity  to  one  another,  but  none 
of  them  having  otolites  preserved  in  situ,  is  cited  as  an  argument  against 
their  having  met  their  death  suddenly  or  in  shoals.  The  peculiar  struc- 
ture and  composition  of  otolites  favor  their  preservation  in  the  fossil 
state,  hence  it  is  not  surprising  that  they  sliould  occur  in  considerable 
abundance  and  variety  throughout  the  Tertiary  and  even  older  horizons. 
Eather  is  it  the  converse  proposition  which  excites  wonder;  for  when  we 
consider  the  number  of  forms  represented  solely  by  ear-bones,  it  is  diffi- 
cult to  understand  why  not  a vestige  of  other  parts  of  the  skeleton  re- 
mains, 
s 


114 


SYSTEMATIC  PALEONTOLOGY 


The  otolites  of  Cyclostomes  and  cartilaginous  fishes  consist  of  irregu- 
lar and  loosely  united  aggregations  of  lime  carbonate;  those  of  Teleos- 
tomes,  on  the  other  hand,  are  dense  porcellanous  bodies  composed  of 
microscopic  crystals  of  calcite,  excellently  adapted  for  fossilization.  The 
proportion  of  calcite  frequently  amounts  to  98  per  cent  of  the  whole, 
and  the  organic  matter  rarely  exceeds  4 per  cent.  Although  extremely 
variable  in  form  and  size,  nothing  can  be  predicated  from  these  char- 
acters as  to  the  proportions  of  the  complete  fish.  The  sculpturing  of 
tiie  external  surface,  however,  has  been  found  fairly  distinctive  for  cer- 
tain families;  for  instance,  it  is  more  or  less  tuberculose  among  the 
Gadidae,  Sciaenidae,  etc,,  and  radially  folded  among  the  Pekcidae 
and  Spaeidae. 

Otolites  are  secreted  in  a few  definite  regions  of  the  auditory  appa- 
ratus. A small  one,  termed  by  Koken  the  lapillus,  is  formed  in  a por- 
tion of  the  labyrinth  known  as  the  vestibule ’’  or  utriculus;  another 
{asteriscus  of  Koken)  occurs  in  the  posterior  prolongation  of  the  otolite- 
sac  (sacculus),  and  the  principal  ear-stone  in  the  center  of  the  sac  proper. 
The  principal  otolite  (sagitta  of  Koken)  occupies  a constant  position 
with  reference  to  the  investing  sacculus,  partaking  of  its  shape  and 
being  attached  to  its  inner  wall;  and  accordingly  it  is  capable  of  being 
precisely  oriented,  even  when  found  in  the  detached  fossil  condition. 
That  is  to  say,  a dorsal  and  ventral,  anterior  and  posterior,  and  inner 
and  outer  side  are  almost  always  to  be  recognized,  as  well  as  the  side  of 
the  head  to  which  it  belongs.  But  on  the  other  hand  the  configuration, 
and  in  the  opinion  of  some  excellent  authorities,  even  the  surface  mark- 
ings of  fish  otolites  are  dependent  on  the  variable  form  of  the  enclosing 
membranous  sac,  and  are  by  no  means  constant  within  specific  or  even 
generic  limits.^ 


1 “ Hasse  halt  auch  die  Form  der  Otolithen  fiir  onvvichtig,  als  ein  mit  der  Form 
des  Sacculus  sich  anderndes  Moment.  . . . Die  Gestalt  der  Otolithen  ist  allerdin^s  in 
^ewissen  Grenzen  variabel,  in  Zusammeuhange  mit  den  individuelleu  Schwankunj^en 
der  Sacculus-Form,  welcher  sie  sich  anpasst.  Audi  ist  das  Wachsthum  vorwieg:end 
auf  die  aussere  Seite  anjj^evviesen,  welche  frei  im  Sacculus  liegt ; ....  dementsprechend 
ist  das  Wachsthum  der  iiusseren  Seite  unregelmassiger,  uud  gerade  die  auf  die  Scul])tur 
derselben  sich  griindenden  Merkmale  . . . erwiesen  sich  ofters  als  ungeeignet,  well  sie 
sich  durch  Vergrosserung  des  Gehorsteines  zu  leicht  verwischen.” — E.  Koken,  Ueber 
Fisch-Otolithen  etc.  {Zeitschr.  d.  d.  geol.  Ges.,  vol.  xxxvi,  1SS4,  p.  51S). 


MARYLAND  GEOLOGICAL  SURVEY 


115 


Xevertlieless,  the  structure  and  topography  of  these  minute  and  ap- 
parently insignificant  bodies  have  been  investigated  with  great  care,  and 
a precise  nomenclature  established.  For  the  depression  extending  from 
the  anterior  margin  backward  in  a horizontal  direction  on  the  flat  or 
concave  inner  side,  Koken  has  proposed  the  designation  of  sulcus  acusti- 
cus,  and  this  he  regards  as  furnishing  the  most  important  diagnostic 
characters.  The  sculpture  of  the  inner  and  outer  sides,  and  nature  of 
the  peripheral  border,  whether  sharp  or  thickened,  smooth,  folded,  den- 
ticulated or  incised,  and  various  minor  characters  of  like  nature  are  all 
taken  into  account  in  the  attempt  to  identify  detached  specimens. 
Their  size,  too,  is  held  to  be  an  important  distinguishing  character. 

The  most  painstaking  investigations  on  fossil  otolites  from  both  our 
own  and  European  Tertiaries  are  those  of  Professor  Koken,"  and  refer- 
ence should  be  had  to  his  writings  by  all  interested  in  this  snbject.  A 
summary  of  the  earlier  literature  is  given  by  him  in  the  first  paper  cited 
below.  If  any  are  inclined  to  question  the  accuracy  of  his  determina- 
tions of  genera  and  species,  the  opportunity  is  certainly  open  for  more 
extended  comparisons  with  recent  and  fossil  forms. 

Otolites  occur  rather  frequently  in  the  Eocene  of  Maryland,  but  only 
a few  have  been  found  in  the  Miocene  at  Plum  Point.  A few  typical 
examples  are  shown  in  Plate  XII,  Figs.  4-G,  but  further  than  to  say  that 
they  bear  a general  resemblance  to  those  of  the  Gadidae,  their  identi- 
fication is  not  attempted  here. 

Occurrence. — Xanjemoy  Formation.  Port  Tobacco,  2^  miles  above 
Popes  Creek,  Woodstock. 

Collection. — IMaryland  Geological  Survey. 

COPROLITES. 

Polled  cylindrical  bodies  of  amorphous  structure  and  very  suggestive 
of  fossil  fish  excrement  are  occasionally  found  at  a few  localities  in  the 
Eocene  of  IMaryland  and  Virginia.  Tlie  occurrence  of  coprolites  of  enor- 
mous size  in  the  Miocene  of  Virginia  has  been  known  for  a long  time." 

Lor.,  rlt.,  pp.  500-565. — Neue  Untersucliungen  an  tertiaren  Fisch-Otolithen, 
vol.  xl,  1888,  pp.  274-805. 

Wyman,  Notice  of  Remains  of  Vertebrated  Animals  found  at  Richmond, Virginia, 
Amer.  Jour.  Sci.,  ser.  ii,  vol.  x,  1850,  p.  285. 


116 


SYSTEMATIC  TALEOXTOLOGY 


ARTHROPODA. 

Class  CRUSTACEA. 

Superorder  M ALACOSTR ACA. 

Order  DECAPODA. 

Family  CANCROIDEA. 

Description. — Claws  belonging  to  an  indeterminate  genus  of  the 
Cancroidea  are  abundant  in  the  bed  underlying  the  indurated  ledge  at 
Upper  Marlboro. 

All  of  the  specimens  are  so  fragmentary  that  no  attempt  is  made  to 
illustrate  the  forms. 

Collection. — Maryland  Geological  Survey. 

Superorder  OSTRACODA. 

Family  BAIRDIIDAE. 

Genus  BYTHOCYPRIS  Brady. 

Bythocitpeis  subaequata  n.  sp. 

Plate  XVI,  Pigs.  1-4. 

Description. — Carapace  about  1.0  mm.  in  length,  elongate,  snbcylin- 
drical  or,  perhaps  better,  siibreniform,  the  dorsal  outline  arcuate,  the 
ventral  slightly  hollowed,  and  the  ends  rounded  and  nearly  equal,  the 
posterior  a trifle  blunter  than  the  anterior;  end  view  nearly  circular, 
dorsal  and  ventral  views  lanceolate,  with  the  greatest  thickness  about 
the  middle  of  the  posterior  half;  left  valve  slightly  overlapping  the 
right  along  its  ventral  edge;  surface  smooth  or  very  finely  granulose. 
Inner  side  of  valves  with  simple  thin  edges,  and  within  these,  except 
along  the  dorsal  border,  a thin  bevelled  plate,  mnch  the  widest  an- 
teriorly. 

There  are  numerous  fossil  and  recent  Ostracoda,  mostly  of  otherwise 
widely  diverging  genera,  that  have  a carapace  similar  to  this,  but  nom^ 
was  found  exactly  matching  it. 


MAKYLAXD  GEOLOGICAL  SURVEY 


117 


Occurrence. — Aquia  Formatiox.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Bythocypris  parilis  n.  sp. 

Plate  XVI,  Figs.  5-8. 

Description. — Carapace  about  1.0  mm.  long,  and  nearly  or  quite  0.5 
mm.  high;  reniform,  strongly  arched  dorsally,  very  slightly  sinuate  or 
straight  in  the  ventral  portion  of  the  outline,  and  with  the  ends  rounded 
and  very  nearly  equal,  the  posterior  outline  however  being  usually  a 
trifle  oblique  above,  and  the  turn  into  the  basal  line  slightly  lower  than 
at  the  front  end;  point  of  greatest  thickness  above  the  middle,  the  slope 
toward  the  ventral  edge  being  flatter  than  elsewhere;  edge  view  elongate, 
snbelliptical,  the  anterior  extremity  more  acute  than  the  posterior,  the 
latter  being  comparatively  blunt.  Left  valve  slightly  overlapping  the 
right  both  above  and  below,  its  ventral  edge  somewhat  thickened  in  the 
middle  and  bordered  along  the  anterior  and  posterior  thirds  of  its  extent 
by  a sharply  impressed,  thin  line.  Surface  generally  appearing  quite 
smooth,  but  under  favorable  circumstances  very  small  scattered  pnnctae 
may  be  observed.  Interior  of  valves  with  the  marginal  plate  well  de- 
veloped and  widest  in  front. 

This  carapace  is  relatively  higher,  has  a more  arcuate  back,  and  less 
acute  anterior  extremity  (in  edge  view)  than  its  associate  B.  subaequata. 
It  is  distinguished  further  by  the  dorsal  overlap  of  the  valves  and  in  the 
greater  development  of  the  internal  marginal  plate. 

Occurrence. — Aquia  Formatiox.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Family  CYTHERELLIDAE. 

Genus  CYTHERELLA  Jones. 

Cytherella  marlboroexsis  n.  sp. 

Plate  XVI,  Figs.  9-13. 

Description. — Carapace  nearly  regularly  ovate,  the  height  and  length 
about  as  two  is  to  three;  0.9  or  1.0  mm.  in  length;  ventral  portion  of 
outline  somewhat  less  convex  than  the  dorsal.  Eight  valve  much  larger 
than  the  left  and  projecting  beyond  it  all  around.  Edge  view  obtusely 
lanceolate,  with  both  extremities  blunt,  the  posterior,  the  more  so,  and 


118 


SYSTEMATIC  PALEONTOLOGY 


much  thicker  than  the  other;  end  view  snhovate.  Valves  eompara- 
tively  thin  for  this  genus,  the  marginal  groove  of  the  right  valve  rela- 
tively narrow  though  sharply  defined.  Interior  of  right  valve  with  two 
snhovate  smooth  spaces,  situated  one  in  the  anterior,  the  other  in  the 
posterior  half,  and  around  them  concentric  rows  of  small  pnstnles.  Sur- 
face smooth  or  minutely  punctate. 

No  known  Tertiary  species  agrees  very  closely  with  this.  The  well- 
known  C.  compressa  (Miinster),  has  a similar  edge  view,  as  have  also 
several  other  species,  hnt  otherwise,  the  form  of  its  carapace,  especially 
the  ventral  portion  of  the  outline,  is  quite  different.  The  Cretaceous 
C.  ovata  is  probably  a closer  relative  but  differs  obviously  in  its  edge 
and  end  views. 

Occurrence. — Aquia  Foemation.  Tipper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Cytiierella  submarginata  n.  sp. 

Plate  XVI,  Figs.  14,  15. 

Description. — Carapace  about  1.0  mm.  in  length,  somewhat  oblong, 
rounded  at  the  ends,  the  posterior  end  a little  wider  and  its  margin 
more  oblique  above  and  merging  more  gradually  into  the  very  slightly 
arcuate  dorsal  outline  than  the  anterior;  ventral  margin  straight,  edge 
view  subcuneiform,  end  view  subovate.  Valves  compressed  convex, 
thickest  posteriorly,  with  an  obscurely  defined  broad  depression  near 
the  midlength  and  mostly  above  the  center  of  the  valves.  A narrow 
but  distinct  rim  borders  the  two  ends.  Surface  smooth. 

Of  this  species  only  the  single  valve  figured  has  been  seen.  Com- 
pared with  described  species  it  was  found  to  agree  rather  well  with  C. 
londinensis  Jones  a Lower  Eocene  species  from  London,  Eng.,  but  after 
a closer  examination  it  was  decided  that  it  could  not  be  justly  referred 
to  that  species.  As  described  and  figured  C.  londinensis  must  have  quite 
a different  appearance  in  edge  views,  due  to  the  more  uniform  convexity 
of  its  valves.  The  central  depression  and  marginal  rims  as  well  as  its 
different  outline,  will  serve  to  distinguish  C.  submarginata  at  once  from 
C.  marlhoroensis  with  which  it  is  associated. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 


MARYLAND  GEOLOGICAL  SURVEY" 


119 


Family  CYTHERIDAE. 

Genus  CYTHERE  Muller. 

Cytpiere  marylandica  n.  sp. 

Plate  XVI,  l"igs.  16-18. 

Description. — Carapace  about  1.0  mm.  in  length  and  0.55  mm.  in 
height  and  thickness,  suhovate  in  outline;  hinge  straight,  half  the  en- 
tire length  of  carapace,  ventral  outline  broadly  arcuate;  anterior  end 
obliquely  rounded,  most  prominent  in  the  lower  half  and  much  wider 
than  the  posterior  end;  the  latter  is  neatly  rounded  below,  obtusely  angu- 
lar above  the  middle,  then  straight  or  slightly  sinuate  to  the  subangular 
extremity  of  the  hinge  line.  Valves  unequal,  the  left  overlapping  the 
right,  very  convex  and  swollen  in  the  middle  and  thickest  near  the 
ventral  edge.  The  swollen  region  of  the  valves  is  of  subtriangular  shape 
and  sharply  defined  Avhere  it  rises  from  the  relatively  small,  compressed, 
terminal  remnants  of  the  surface.  Of  these  remnants  the  posterior  is 
more  depressed  (it  may  appear  like  a flattened  border)  and  narrower  than 
the  anterior  one,  and  both  are  marked  with  shallow  pits  arranged  in 
rather  obscure  concentric  series.  The  surface  of  the  swollen  region  is 
more  distinctly  pitted,  Avith  the  pits  arranged  in  the  loAver  half  betAveen 
more  or  less  sharp  longitudinal  curved  riblets  and  much  less  regularly 
in  the  upper  half.  Sometimes  the  SAvelling  is  terminated  beloAv  by  one 
or  tAvo  ribs  more  prominent  and  stronger  than  the  rest.  Edge  Anew 
snbovate,  Avith  the  ends  produced;  end  vieAV  subtriangular  AAuth  the  lat- 
eral lines  rather  strongly  convex.  Hingement  consists  as  usual  in 
Cythere  of  large  lateral  teeth  and  connecting  har. 

This  seems  to  be  a Avell-marked  species  Avith  not  very  close  relations 
to  C.  trigonula  Jones  and  C.  triangularis  (Peuss)  Jones.  From  lioth 
it  differs  in  outline,  the  former,  varying  further  in,  having  also  a finer 
surface  punctation,  a much  more  triangular  end  vieAV,  and  relatively 
very  slightly  compressed  ends  causing  the  edge  vieAv  to  he  equally  dif- 
ferent. C.  triangularis  agrees  better  in  end  and  edge  vieA\"s  but  its  sur- 
face differs  decidedly,  being  smooth,  shining,  and  beset  Avith  scattered 
setae.’’  Another  of  the  species  described  by  Jones  in  his  Monograph  of 
the  Tertiary  Entomostraca  of  Ehigland,  es])ecially  since  he  nuoitions 
that  he  has  a scarcely  distinguishable  A-ariety  of  it  from  the  middle  Ter- 


120 


SYSTEMATIC  PALEONTOLOGY 


tiary  of  Maryland,  may  be  compared  with  C.  marylandica.  This  is 
Cythere  pmictata  (Miinster).  Judging  from  illustrations  alone  the  pres- 
ent species  must  be  quite  distinct  and  so  obviously  that  it  seems  highly 
improbable  that  the  American  variety  of  Munster’s  species  mentioned  by 
Jones,  is  the  same  as  the  one  above  described. 

Occurrence. — Aquia  Fokmation.  Upper  Marlboro,  Brooks  Estate 
near  Seat  Pleasant. 

Collection. — Maryland  Geological  Survey. 

Genus  CYTHEREIS  Jones. 

Cytheeeis  bassleri  n.  sp. 

Plate  XVI,  Figs.  19-21. 

Description. — Carapace  oblong,  length  0.80  to  0.85  mm.,  widest  and 
rounded  anteriorly;  the  posterior  edge  more  or  less  angular  in  the  mid- 
dle, straight  or  slightly  sinuate  above  to  the  angular  extremity  of  the 
hinge,  and  with  two  or  three  spines  projecting  from  the  slightly  convex, 
lower  half;  edges  with  a thickened  rounded  rim,  becoming  obsolete  near 
the  center  of  the  flattened  ventral  region;  hinge  line  straight  except  at 
the  antero-cardinal  angle  which  is  thickened  and  prominent;  ventral 
outline  slightly  sinuate.  Valves  equal,  with  a rounded  sub-central  node, 
sometimes  obscured  by  a network  of  small  ridges,  and  a sharp  ventral 
ridge  rising  gradually  from  its  inception  at  the  antero-ventral  angle  and 
ceasing  abruptly  at  a point  about  one-fourth  of  the  length  of  the  valve 
from  its  posterior  extremity.  A less  prominent  ridge  runs  from  the 
high  end  of  the  ventral  ridge  in  a slightly  oblique  direction  to  the  post- 
cardinal angle  and  then  turns  forward.  The  whole  surface  is  covered 
with  rather  large  pits  arranged  in  more  or  less  irregular  curved  series, 
the  space  between  the  rows,  especially  over  the  central  portion  of  the 
valves  being  raised  into  thin  and  sometimes  coalescing  ridges. 

This  species  presents  more  or  less  close  affinities  with  no  less  than 
six  of  the  species  of  Cythere  figured  by  Bosquet  in  his  excellent  Mono- 
graph of  the  Ostracoda  of  the  Tertiary  deposits  of  France.^  These  are 
C.  hehertiaiia  Bosq.,  C.  thierensiana  Bosq.,  C.  desliayesiana  Bosq.,  C. 

’ Desc.  des  Entomostrace’s  Fossiles  des  Terrains  Tertiaires  de  la  France  et  de  la 
Belgique.  Mem.  Couron.  Acad.  Belg.,  Tome  xxiv,  1851. 


MARYLAND  GEOLOGICAL  SURVEY 


121 


angusticostaia  Bosq.,  C.  macropora  Bosq.  and  C.  edwardsi  (Roemer),  all 
Eocene  species  except  the  last,  which  is  a widely  distributed  Miocene 
fossil.  Despite  the  often  striking  similarities  presented,  not  one  of  the 
European  species  mentioned  agrees  closely  enough  in  all  respects  to 
justify  a reference  of  the  Maryland  form  to  it. 

Cytliereis  hassleri,  which  I name  in  honor  of  my  able  and  indefatigable 
assistant,  Mr.  R.  S.  Bassler,  seems  to  be  a common  fossil  at  Dpper  Marl- 
boro. Considering  that  the  specimens  studied  present  considerable 
variation  in  surface  sculpture,  it  is  possible  that  they  represent  more 
than  a single  specific  type.  I have  also  a specimen  from  the  Cretaceous 
at  Vincentown,  N”.  J.,  which  can  scarcely  be  distinguished  from  the 
Upper  Marlboro  specimen  figured. 

Occurrence. — x\quia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Genus  CYTHERIDEA  Bosquet. 

Cytheridea  perarcUx\.ta  n.  sp. 

Plate  XVI,  Fig.  22,  23. 

Description. — Carapace  1.1  mm.  long,  0.6  mm.  high,  strongly  and,  ex- 
cepting the  acuminate  posterior  extremity,  rather  uniformly  convex, 
obliquely  acute-ovate  in  outline;  ventral  edge  straight  to  the  acute  pos- 
terior extremity,  the  sharpness  of  which  is  emphasized  by  a small  spine; 
anterior  outline  wide  and  regularly  rounded,  and  armed  with  five  or 
six  spines;  dorsal  side  strongly  arcuate,  the  curve  straightening  some- 
what as  it  nears  the  posterior  end.  Central  portion  of  surface,  over  a 
space  corresponding  in  shape  with  the  outline  of  the  valves,  marked 
with  eleven  or  twelve  approximately  vertical  furrows,  each  including 
a row  of  small  punctures.  Beyond  this  space  the  surface  is  smooth,  ex- 
cepting toward  the  posterior  end  where  an  obscurely  wrinkled  appearance 
may  be  observed.  Ventral  edge  of  right  valve  with  a narrow  bevel  in- 
ward. Hinge  as  required  by  the  genus,  consisting  of  a series  of  small 
denticles  at  each  end  of  the  hinge  in  right  valve  and  corresponding 
sockets  in  the  left  valve.  Edge  view  broadly  lanceolate,  thickest  near  the 
middle  length  and  slightly  more  attenuate  behind  than  in  front;  end 
view  subcircular. 


122 


SYSTEMATIC  PALEONTOLOGA" 


At  first  it  was  believed  that  this  form  might  he  regarded  as  a variety 
of  Cytheridea  mulleri  (Miinster),  a common  and  widely  distributed 
European  Tertiary  and  Becent  species.  However  a more  careful  com- 
parison brought  out  so  many  differences  that  it  seemed  best  to  rank  them 
as  distinct  species.  This  conclusion  was  confirmed  by  finding  almost 
unquestionable  C.  mulleri  associated  with  C.  perarcuata  at  Woodstock, 
while  C,  intermedia  (Reuss)  which  Jones  considers  a close  variety  of 
C.  mulleri,  was  found  rather  abundantly  in  association  with  specimens 
agreeing  closely  with  Jones’  C.  deUlis,  at  Upper  Marlboro.  C.  perarcu- 
ata differs  from  all  of  these  forms  in  the  restricted  extent  of  its  surface 
markings,  in  wanting  a mesial  furrow,  in  its  relatively  greater  height 
and  more  strongly  arcuate  dorsal  outline.  Its  edge  view  furthermore 
is  decidedly  different,  the  central  portion  being  thicker,  while  the  ends, 
the  posterior  especiall}q  are  thinner. 

Occurrence. — Nanjemoa^  Formation.  AVoodstock.  Aquia  Forma- 
tion. Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 


MOLLUSCA. 

Class  CEPHALOPODA. 

Subclass  TETRABRANCHIATA. 

Order  NAUTILOIDEA. 

Suborder  ORTHOCHAENITES. 

Family  CLYDONAUTILIDAE. 

Genus  HERCOGLOSSA  Conrad. 

IIercoglossa  tuomeam  n.  sp. 

Plates  XVII-XIX. 

NautiluH  ,sp.  Tuomey,  1842,  Amer.  Jour.  Sci.,  vol.  xliii,  p.  187. 

Nautilus  sp.  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  A"o1.  xv,  p.  4. 

Nautilus  sp.  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  63,  pi.  ix,  tig.  1. 

Description. — Shell  large;  aperture  v'ide,  narrowing  rapidly,  without 
curving  to  a narrow  and  sharply  rounded  periphery;  ventral  saddles  of 


MARYLAND  GEOLOGICAL  SURVEY 


123 


moderate  size;  lateral  lobes  regularly  but  moderately  rounded;  lateral 
saddles  narrower  and  sharper  than  the  other  saddles;  umbilici  not  small; 
shell  thick  (2-8  mm.),  marked  by  fine,  distinct,  closely-set  lines  of 
growth,  which  sweep  shar])ly  back  on  the  periphery. 

This  species  is  distinguished  from  If.  (E nclimatoceras)  ulriclii  by  its 
much  less  prominent  ventral  saddles,  and  by  its  less  uniformly  rounded 
transverse  section,  the  sides  being  almost  without  curvature  down  almost 
to  the  very  periphery. 

The  nautiloid  shell  which  Tuomey  roughly  described  without  naming 
was  from  the  James  river  and  from  a horizon  exactly  corresponding  to 
our  Popes  Creek  occurrence.  There  is  little  doubt  that  it  was  this 
species. 

Diameter  (restored)  of  coil  of  largest  specimen  about  400  mm. 

Occurrence. — Xaxjemoy  Formation.  Popes  Creek  (abundant). 
Aquia  Formation.  Clifton  Beach  (fragments  rare). 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University. 


Class  GASTROPODA. 

Order  OPISTHOBRANCHIATA. 

Suborder  TECTIBRANCHIATA. 

Family  ACTAEONIDAE. 

Genus  TORNATELLAEA  Conrad. 

Tornatellaea  BELLA  Coiirad. 

Plate  XX,  Figs.  1,  la,  2. 

Tornatellaea  bella  Conrad,  1860,  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  ser.,  vol.  iv, 
p.  294,  pi.  xlvii,  tig.  23. 

Tornatella  bella  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Tornatella  bella  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  63. 

Description. — Ovate,  spire  conical;  revolving  lines  numerous,  im- 
pressed, punctate  striate.”  Conrad,  18G0. 

Shell  solid,  ovate  in  profile,  six-whorled;  surface  with  uniform,  punc- 
tate, spiral  grooves,  crossed  only  by  lines  of  growth  and  regularly  un- 


124-. 


SYSTEMATIC  PALEOXTOLOGY 


diilating  in  width;  spire  short,  conical,  acuminate;  whorls  slightly  con- 
vex; body  whorl  more  than  half  the  length  of  the  shell,  moderately 
convex;  suture  distinct;  outer  lip  sometimes  crenulate;  columella  with 
two  pronounced  oblique  plicae. 

Length,  15  mm.;  width,  8 mm. 

Occurrence. — Xaxjemoy  Foematiox.  West  of  Port  Tobacco.  Wood- 
stock,  1 mile  southeast  of  Piscataway.  Aquia  Foematiox.  Aquia 
Creek,  Potomac  Creek,  1 mile  northeast  of  Piscataway,  Upper  Marlboro. 

Collections. — Maryland  Geological  Survey,  Philadelphia  Academy  of 
Natural  Sciences,  U.  S.  National  Museum. 

Family  RINGICULIDAE. 

Genus  RINGICULA  Deshayes. 

Eixgicula  dalli  Clark. 

Plate  XN,  Figs.  3,  3a. 

Ringicula  dalU  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Ringicula  dalli  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  64,  pi.  ix,  figs.  3a,  36. 
Ringicula  dalli  Aldrich,  1897,  Bull.  Amer.  Pal.  No.  8,  p.  8,  pi.  ii,  fig.  6. 

Description. — Shell  small,  five-whorled;  surface  of  last  four  whorls 
strongly  striate  spirally;  spire  elevated,  acuminate;  body  whorl  much 
inflated;  outer  lip  much  thickened  and  crenulate  within;  columella  with 
thick  callous  and  with  two  strong  plaits.’’  Clark,  1896. 

Length,  3 mm.;  width,  2 mm. 

Occurrence. — Nax.temoy  Foematiox.  IVoodstock. 

Collection. — Maryland  Geological  Survey. 

Family  SCAPHANDRIDAE. 

Genus  CYLICHNA  Loven. 

Cylichna  vexusta  Clark. 

Plate  NX,  Figs.  4,  4a. 

Cylichna  vemu^ta  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Cijlichna  vemisia  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  64,  pl.'ix,  figs.  2a,  26. 

Description. — “ Shell  small,  elongate-ovate,  rather  globose;  surface 
spirally  striate;  spire  depressed;  columella  with  small  obscure  plait.” 
Clark,  1896. 


MARYLAND  GEOLOGICAL  SURVEY 


125 


The  spire  is  usually  perforate,  and  the  revolving  lines  alternate  and 
punctate.  It  most  closely  resembles  C.  aldrichi  Langdon,  from  which  it 
is  distinguished  by  being  proportionally  longer,  less  cylindrical  in  out- 
line, and  with  the  spire  less  strongly  perforate. 

Length,  7 mm.;  width,  3.5  mm. 

Occurrence. — Xanjemoy  Formation.  West  of  Port  Tobacco,  Head  of 
Xanjemoy  Creek,  Woodstock.  Aquia  Formation.  1 mile  southeast 
of  Mason  Springs,  Potomac  Creek,  2 miles  below  Potomac  Creek,  1 
mile  northeast  of  Piscataway,  Clifton  Beach. 

Collections. — Johns  Hopkins  University,  ]\raryland  Geological  Survey. 

Superfamily  TOXOGLOSSA. 

Family  PLEUROTOMIDAE. 

Genus  PLEUR.OTOMA  Lamarck. 

Pleurotoma  harrisi  Clark. 

Plate  XX,  Figs.  5,  5a,  6. 

Tleurotoma  harrin  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Pleurotoma  harrisi  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  64,  pi.  ix,  figs.  4a, 
4&. 

Descri])tion. — Shell  of  moderate  size,  elongate,  five  or  six  whorled; 
surface  with  distinct,  revolving  lines  of  varying  size,  crossed  by  trans- 
verse ridges;  aperture  narrow,  with  long  straight  canal.’’  Clark,  1896. 

The  lower  half  of  the  whorl  is  strongly  convex  and  is  strongly  orna- 
mented with 'revolving  lines,  alternating  in  size,  and  is  crossed  on  the 
shoulder  by  oblique  nodular  ridges.  The  upper  half  of  the  whorl  is 
flat,  with  very  faint  revolving  lines,  except  one  or  two  strong  ones  about 
the  middle  of  the  flat  zone.  The  aperture  narrows  rapidly  toward  the 
base,  the  body  whorl  partaking  of  the  constriction.  The  canal  is  very 
long,  straight,  and  narrow. 

Length,  30  mm.;  width,  8 mm. 

Occurrence. — Aquia  Formation.  Potomac  Creek,  2 miles  below  Po- 
tomac Creek,  1 mile  southeast  of  Mason  Springs. 

Collection. — Maryland  Geological  Survey. 


126 


SYSTEMATIC  PALEOXTOLOGY 


Pleueotoma  potomacexsis  n.  sp. 

Plate  XX,  Figs.  7,  7a. 

Description. — Shell  attenuate,  with  spire  and  beak  of  equal  length; 
aperture  narrow;  beak  long  and  straight;  whorls  seven,  with  four  more 
in  the  nnclens;  few  large,  raised,  revolving  lines  on  and  below  the  shoul- 
ders; nnmerons  fine,  proximate  lines  between  these,  and  covering  the 
entire  whorl;  two  ])rominent,  raised,  revolving  lines  below  the  sntnre, 
the  lower  more  prominent;  shoidder  with  acnte  nodes,  carinated  by  one 
or  two  of  the  major  revolving  lines;  lines  of  growth  faint. 

Some  varieties  of  P.  nasnta  Whitfield  are  very  similar  to  this  species. 
It  is  intermediate  between  that  species  and  P.  harrisi  Clark. 

Length,  31  mm.;  width,  8 mm. 

Occurrence. — Aquia  Fokmatiox.  1 mile  northeast  of  Piscataway,  2 
miles  below  Potomac  Creek. 

Collection. — ]\Iar3dand  Geological  Survey. 

Pleueotoma  ducateli  n.  sp. 

Plate  XX,  Fig.  8. 

Description. — Surface  smooth,  save  for  faint,  impressed,  revolving 
lines  which  become  stronger  just  below  the  sntnre,  and  very  strong  on 
the  beak;  sntnre  very  distinct;  columella  straight,  striated  spirally;  lines 
of  growth  faint,  with  broad  sinus  below  the  sntnre. 

Length,  10  mm.;  width,  4 mm. 

Occurrence. — Aquia  Foematiox.  1 mile  southeast  of  Mason  Springs. 

Collection. — IMaryland  Geological  Survey. 

Pleueotoma  ta'soxi  n.  sp. 

Plate  XX,  Fig.  0. 

Description. — Shell  eight-whorled;  body  whorl  about  half  the  length 
of  shell;  month  contracting  but  slightly  toward  beak;  body  whorl  with 
sixteen,  oblique,  longitudinal  ribs,  strongly  nodular  where  crossed  by 
the  large,  elevated,  revolving  lines;  eight  strong,  revolving  lines  on  the 
body  whorl  helow  the  shoulder,  and  nnmerons  fainter  ones  below,  on  the 
beak.  All  the  whorls  are  concave  above  the  shoulder,  and  nnscnlptnred, 
save  for  lines  of  growth  and  for  a strong,  raised,  nodular,  snbsntnral 


MARYLAND  GEOLOGICAL  SURVEY 


127 


line.  Whorls  of  the  spire  with  four  nodular  revolving  lines  below  the 
shoulder. 

Length,  12  mm.;  width,  -1  mm. 

Occurrence. — Aquia  Formation.  1 mile  southeast  of  Mason  Springs. 

Collection. — Maryland  Geological  Survey. 

Subgenus  HEMIPLEUROTOMA  Cossmann. 

Pleurotoma  (Hemipleurotoma)  childreni  Lea. 

Plate  XX,  Figs.  10,  11. 

Pleurotoma  childreni  Lea,  1833,  Contrib.  to  GeoL,  p.  137,  pi.  iv,  fig.  132. 

Pleurotoma  denticula  var  Harris,  1899,  Bull.  Amer.  Pal.,  No.  11,  p.  12,  pi.  i,  figs. 

21,  22. 

Description. — Shell  fusiform,  tiirrited,  transversely  striate,  granu- 
late on  the  larger  part  of  the  whorl;  substance  of  the  shell  rather  thick; 
spire  elevated,  obtuse  at  apex;  whorls  about  nine,  siibcanaliciilate  above; 
mouth  long  and  narrow,  one-third  the  length  of  the  shell.”  Lea,  1833. 

Our  specimens  vary  considerably  in  the  smaller  details  of  sculpture, 
but  all  seem  to  fall  within  the  limits  of  variation  of  the  Alabama  form. 
Whether  they  are  the  same  as  the  French  species  P.  denticula  Bast,  to 
which  Professor  Harris  assigns  the  Alabama  form  is  a question  that 
cannot  be  settled  here.  They  agree  with  it  well  enough  to  fall  into  the 
subgenus  Hemipleurotoma  of  which  P.  denticula  is  the  type. 

Length,  12  mm.;  width,  3.5  mm. 

Occurrence. — Aquia  Formation.  1 mile  southeast  of  Mason  Springs, 
2 miles  below  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 

Pleurotoma  piscatavensis  n.  sp. 

Plate  XX,  Fig.  12. 

Description. — Shell  fusiform,  seven-whorled,  carinated;  lines  of  growth 
distinct;  revolving  lines  absent  above  the  shoulder,  one  to  three  in  num- 
ber below  the  shoulder;  beak  marked  only  by  lines  of  growth;  nucleus 
three-whorled,  smooth;  following  whorls  of  the  spire  with  oblique  ])li- 
cae,  extending  from  suture  to  suture;  body  whorl  with  about  ten  acute 
nodes,  confined  to  the  suture. 


128 


SYSTEMATIC  PALEOXTOLOGA' 


Length,  11  mm.;  width,  4 mm. 

Occurrence. — Aquia  Foematiox.  1 mile  northeast  of  Piscataway. 

Collection. — Maryland  Geological  Survey. 

Genus  MANGILIA  Risso. 

Subgenus  PLEUROTOMELLA  Venill. 

Maxgilia  (Pleurotomella)  bellistriata  Clark. 

Plate  XX,  Figs.  13,  13a. 

Mangilia  {Fletirotomella)  bellistriata  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv, 
p.  4. 

Mangilia  {Pleurotomella)  bellistriata  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  65, 
pi.  ix,  flg.  5. 

Description. — Shell  small,  snhfnsiform,  with  a rather  short,  pointed 
spire,  and  ahont  five  whorls;  body  whorl  large,  somewhat  infiated;  earlier 
whorls  nearly  flat;  surface  scnlptnred  with  numerous,  alternating,  larger 
and  smaller  spiral  threads,  crossed  hy  fine,  wavy  lines,  and  by  irregu- 
larly spaced,  oblique  ribs,  about  twenty  in  number  on  the  body  whorl; 
ribs  strongest  at  the  shoulder,  gradually  disappearing  both  posteriorly 
and  anteriorly;  behind  the  shoulder  somewhat  excavated;  aperture  nar- 
row.^’ Clark,  1896. 

There  is  a distinct  fold  on  the  columella,  and  the  lines  of  growth  are 
very  slightly  curved. 

Length,  27  mm.  (restored);  width,  13  mm. 

Occurrence. — Xaxjemoy  Foematiox.  Popes  Creek.  Aquia  Forma- 
tiox.  Potomac  Creek. 

Collections. — Johns  Hopkins  University,  Philadelphia  Academy  of 
Xatural  Sciences. 

Family  CANCELLARIDAE. 

Genus  CANCELLARIA  Lamarck. 

Caxcellaria  graciloides  Aldrich,  var. 

Plate  XXI,  Fig.  1. 

Caiicellaria  graciloides  Aldrich,  1898,  The  Nautilus,  vol.  xi,  p.  98. 

Cancellaria  graciloides  1899,  Bull.  Amer.  Pal.,  No.  11,  pp.  28,  29,  pi.  iii, 

tigs.  10,  11. 

Description. — Shell  broadly  fusiform,  spire  elevated,  whorls  6-7, 
rounded,  slightly  shouldered,  cancellated,  first  three  smooth,  on  the 


MARYLAND  GEOLOGICAL  SURVEY 


129 


other^  the  revolving  lines  are  nnmerons,  strongly  defined;  lines  of  growth 
smaller  and  much  finer  than  the  revolving  lines,  sntnre  deeply  im- 
pressed, outer  lip  expanded,  strongly  nodular  within,  columella  with 
three  folds,  aperture  pointed  and  canaliculate  at  base/^  Aldrich,  1898, 

This  abundant  and  variable  form  approaches  too  near  to  some  va- 
rieties of  C.  graciloides  to  be  safely  separated  from  it. 

Length,  13  mm.;  width,  8 mm. 

Occurrence. — A quia  Formation.  1 mile  southeast  of  Mason  Springs. 

Collection. — Maryland  Geological  Survey. 

Cancell  ARIA  sp. 

Plate  XXI,  Fig.  2. 

Several  specimens  of  Cancellaria  were  found  that  are  so  imperfect  and 
immature,  that  it  is  unsafe  to  describe  them  or  even  to  refer  them  to 
any  known  species,  yet  they  are  very  different  from  our  other  Maryland 
species. 

The  figured  specimen  represents  a form  from  the  locality  two  miles 
below  Potomac  Creek  which  also  doubtfully  occurs  at  Potomac  Creek, 
and  which  distantly  recalls  C.  parva  Lea.^  When  .the  adult  is  found 
it  will  probably  be  recognized  as  a new  species. 

Another  form  from  Potomac  Creek  may  be  C.  ulmula  Harris^  or  a 
variety.  This  is  so  imperfect  that  it  does  not  seem  desirable  to  figure  it. 

Occurrence. — Aquia  Formation.  2 miles  below  Potomac  Creek,  Po- 
tomac Creek. 

Collection. — Maryland  Geological  S'urvey. 

Subgenus  NARONA  H.  and  A.  Adams. 

Cancellaria  (Xarona)  potomacensis  n.  sp. 

Plate  XXI,  Figs,  3,  3a. 

Description. — Shell  elongate;  mouth  more  than  half  the  length  of  the 
shell;  spire  short;  whorls  marked  with  distinct,  raised,  flat-topped,  re- 
volving ridges,  with  interspaces  twice  as  broad;  body  whorl  with  twenty 
of  these  ridges,  whorls  of  the  spire  with  six.  Lines  of  growth  and 

^Contrib.  Geol.,  p.  42,  pi.  v,  fig.  141. 

2Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  xlvii,  1895,  p.  66,  pi.  vi,  fig.  6. 


130 


SYSTEMATIC  PALEONTOLOGY 


several  variable,  usually  obscure,  longitudinal  undulations  cross  the 
revolving  ribs,  granulating  them  and  often  reticulating  the  surface. 
Labium  expanded,  grooved  and  cancellated.  Labium  with  two,  distinct, 
oblique  folds  and  numerous  striae,  continuations  of  the  external  revolv- 
ing lines.  Canal  short,  recurved. 

Length,  17  mm.;  width,  8 mm. 

Occurrence. — Aquia  Fokmation.  1 mile  southeast  of  Mason  Springs. 

Collection. — Maryland  Geological  Survey. 


Superfamily  RACHIGLOSSA. 

Family  OLIVIDAE. 

Genus  OLIVULA  Harris. 

Olivula  sp. 

A single  specimen  was  found  which  gives  little  doubt  of  its  generic 
character.  It  is  probably  distinct  from  0.  staminea  (Conrad).  In  the 
imperfect  condition  of  the  specimen  it  is  impossible  to  assign  it  to  any 
species,  new  or  old,  and  a figure  would  show  no  determining  characters. 
Length,  20  mm.;  width,  6 mm. 

Occurrence. — Nanjemoy  Fokmation.  Popes  Creek. 

Collection. — Maryland  Geological  Survey. 

Family  VOLUTIDAE. 

Genus  VOLUTILITHES  Swainson. 

VoLUTiLiTHES  PETROSUS  (Conrad). 

Plate  XXI,  Figs.  4,  5,  5a. 

Valuta  petrosa  Conrad,  1838,  Fossil  Shells  of  the  Tertiary,  No.  3 [1st  Edit.],  p.  29. 
Valuta  petrosa  Conrad,  1835,  Fossil  Shells  of  the  Tertiary,  No.  3 [2nd  Edit.],  p.  41, 
pi.  xvi,  fig.  2. 

Atlileta  tuomeyi  Conrad,  1853,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  vi,  p.  449. 
Valutilithes  {Athleta)  tuomeyi  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 
Volutilithes  {Athleta)  tuomeyi  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  65,  pi.  x, 
figs,  la,  15. 

Description. — “ Shell  subglabrous;  body  whorl  marked  with  from  eight 
to  ten  longitudinal  folds,  terminating  on  the  shoulder  in  compressed 


MARYLAND  GEOLOGICA,!^  SURVEY 


131 


subacute  tubercles,  which  are  also  distinct  on  the  spire:  transversely 
striated  at  base:  two  folds  on  the  columella/^  Conrad,  1833. 

The  Maryland  specimens  are  principally  of  the  tuomeyi  type,  but  the 
normal  form  occurs  with  it  at  most  localities. 

Length,  38  mm.;  width,  25  mm. 

Occurrence. — Xaxjemov:  Formation.  Woodstock,  Popes  Creek;  West 
of  Port  Tobacco.  Aquia  Formation.  Potomac  Creek,  2 miles  b^low 
Potomac  Creek,  1 mile  northeast  of  Piscataway,  1 mile  southeast  of 
Mason  Springs,  Aquia  Creek. 

Collections. — ]\Iaryland  Geological  Survey,  Johns  Hopkins  University, 
Philadelphia  Academy  of  Xatural  Sciences,  U.  S.  Xational  Museum. 

VOLUTILITHES  Sp. 

Plate  XXI,  Figs.  6,  6a. 

Volutilithes  sp.  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Volutilithes  sp.  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  65,  pi.  x,  figs.  2a,  25. 

A fine  cast  of  a large  species  of  Volutilithes  was  obtained  from  the  in- 
durated ledge.  Zone  3,  at  the  Aquia  Creek  bluffs,  and  a very  imperfect 
specimen  from  Potomac  Creek.  It  is  unlike  any  of  the  species  of  Volu- 
tilithes hitherto  described,  but  from  the  fact  that  the  shell  subatance  is 
almost  lacking  no  attempt  will  be  made  to  give  a full  description.  It 
has  a somewhat  compressed  form,  due  to  pressure. 

The  shell  substance  is  extremely  thin,  and  the  surface  is  marked  only 
by  lines  of  growth.  The  tubercles  are  obtuse  and  distant,  and  the  spire 
small. 

Length,  75  mm.;  width,  53  mm. 

Occurrence. — Aquia  Formation.  Aquia  Creek,  Potomac  Creek. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University. 

Genus  CARICELLA  Conrad. 

Caricella  pyruloides  (?)  (Conrad). 

Plate  XXI,  Figs.  7,  8. 

Turhinella  pyruloides  Conrad,  1833,  Fossil  Shells  of  the  Tertiary,  No.  2,  p.  24,  pi.  x, 
fig.  1. 

(?)  Caricella  sp.  Clark,  189.5,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

(?)  Caricella  sp.  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  66,  pi.  xi,  fig.  1. 


132 


SYSTEMATIC  PALEONTOLOGY 


Description. — Pyriform,  ventricose,  smooth;  with  obscure  spiral 
striae  on  the  inferior  half  of  the  body  whorl;  spire  very  short;  apex 
slightly  mammillated;  columella  with  4 distant  oblique  plaits/’  Con- 
rad, 1833. 

The  specimens  which  are  referred  to  this  species  consist  of  the  cast 
and  the  broken  shell  which  are  figured,  and  a still  more  imperfect  cast. 
It  is  not  certain  that  they  belong  to  the  same  species,  or  that  any  of 
them  belong  to  the  species  to  which  they  are  here  referred.  If  they  do 
not  belong  here  they  probably  represent  one  or  more  undescrihed  species. 

Length,  55  mm.;  width,  22  mm. 

Occurrence. — Aquia  Formation.  Potomac  Creek,  Aquia  Creek,  Liv- 
erpool Point. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University. 

Genus  MITRA  Lamarck. 

Mitra  marylandica  Clark. 

Plate  XXI,  Figs.  9,  9a. 

Mitra  marylandica  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Mitra  marylandica  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  66,  pi.  xi,  figs.  4a, 
45  (not  3). 

Description. — Shell  small,  rather  thick,  with  six  (?)  whorls;  surface 
with  numerous,  thickly-set  spiral  threads,  crossed  by  fine  wavy  lines, 
giving  a finely  reticulated  appearance;  spine  moderately  high;  suture 
distinct,  appressed;  shoulder  not  prominent;  aperture  elongated;  col- 
umella nearly  straight,  with  three  plaits.”  Clark,  1896. 

The  essential  character  which  distinguishes  this  species  from  the  fol- 
lowing is  the  lack  of  ribbing. 

Length,  21  mm.;  width,  7 mm. 

Occurrence. — Aquia  Formation.  Pomonkey  Xeck. 

Collection. — U.  S.  Xational  Museum. 

Mitra  pomonkensis  n.  sp. 

Plate  XXI,  Figs.  10,  10a. 

Mitra  sp.  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

3Iitra  sp.  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  66,  pi.  xi,  figs.  3a,  36. 

Description. — Shell  larger  than  M.  marylandica;  whorls  strongly  con- 
vex, and  with  a somewhat  angulated  shoulder  slightly  above  the  middle; 


MAEYLAND  GEOLOGICAL  SURVEY 


133 


sculptured  by  numerous,  approximate,  impressed,  revolving  lines,  and 
variable  longitudinal  ribs,  which  stop  at  the  shoulder,  leaving  a subsu- 
tural  constriction  above  it. 

The  best  specimens  of  this  species  are  in  the  Philadelphia  Academy 
and  are  from  Potomac  Creek. 

The  type  in  the  U.  S.  National  IMuseum  is  now  labelled  ^^‘Near 
Month  of  Potomac  Cr.f  G.  D.  Harris,’^  but  it  was  supposed  when  des- 
cribed to  have  come  from  Pomonkey  Neck. 

Length,  25  mm.;  width,  9 mm.  The  largest  specimen  has  width  of 
12  mm. 

Occurrence. — Aquia  PormaIion.  Pomonkey  Neck,  2 miles  below  Po- 
tomac Creek,  Potomac  Creek,  1 mile  northeast  of  Piscataway. 

Collections. — Maryland  Geological  Survey,  U.  S.  National  Museum, 
Philadelphia  Academy  of  Natural  Sciences. 

Mitra  potomacensis  n.  sp. 

Plate  XXI,  Fig.  11. 

Description. — Shell  small;  whorls  but  slightly  convex,  and  not  con- 
stricted below  the  suture;  revolving  lines  fine,  distinct;  ribs  reaching 
from  suture  to  suture,  and  often  extending  in  one  continuous  line  from 
w^horl  to  whorl;  ribs  usually  sharp  and  narrow. 

Length,  12  mm.;  width,  3.5  mm. 

Occurrence. — Nayjemoy  Formation.  Woodstock,  Popes  Creek. 
Aquia  Formation.  1 mile  northeast  of  Piscataway. 

Collection. — Maryland  Geological  Survey. 

Family  FUSIDAE. 

Genus  LATIRUS  Montfort. 

Latirus  marylandicus  n.  sp. 

Plate  XXI,  Figs.  12,  12a. 

Description. — Shell  subfusiform,  five  or  more  whorled;  body  whorl 
with  fifteen,  blunt,  irregular,  longitudinal  folds,  and  a number  of  re- 
volving ridges,  very  prominent  on  the  shoulder  and  gradually  dying  out 
toward  the  beak;  entire  shell  covered  by  fine,  closely-set,  raised,  revolv- 


134 


SYSTEMATIC  PALEONTOLOGY 


ing  threads,  which  over-ride  both  the  longitudinal  and  the  revolving 
folds,  the  threads  showing  a tendency  to  alternate  in  size;  whorls  of 
spire  with  two,  very  distinct,  revolving  folds;  major  intersecting  sets  of 
sculpture  giving  a reticulate  appearance;  folds  strongly  nodular  at  the 
intersections;  mouth  narrow;  columella  with  two,  strong,  oblique  folds; 
canal  long  and  straight. 

Length,  26  mm.;  width,  11  mm. 

Occurrence. — Aquia  Fokmation.  2 miles  below  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 

Genus  FUSUS  (?)  Lamarck. 

The  following  species  are  referred  to  the  genus  Fusus  without  any 
claim  that  their  biological  affinities  are  with  that  genus  as  now  restricted. 
They  belong  to  that  large  group  of  fossils,  of  approximately  fusoid 
form,  but  indeterminate  generic  relationships. 

Fusus,  (?)  SUBTENUIS  Heilprin. 

Plate  XXII,  Figs.  1,  2. 

Fusus  subtenuis  Heilprin,  1880,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  xxxv,  p.  371, 
pi.  XX,  fig.  4. 

Description. — Shell  fusiform,  of  about  seven  subangular  volutions; 
whorls  ornamented  with  somewhat  obscure  longitudinal  folds,  about 
twelve  on  the  body  whorl,  which  are  cut  by  several  prominent  revolving 
ridges  commencing  at  the  shoulder  angulation;  shoulder  of  the  whorls 
more  or  less  smooth,  with  an  obscure  median  revolving  line,  and  a 
prominent  subsutural  one;  aperture  about  the  length  of  the  spire,  or 
slightly  exceeding  it,  the  canal  gently  curved,  moderately  contracted, 
and  somewhat  expanding  at  the  extremity;  outer  lip  thin,  and  showing 
internally  the  external  ornamentation;  base  with  numerous  revolving 
lines,  which  alternate  in  coarseness.^’  Heilprin,  1880. 

Very  characteristic  specimens  of  this  species  occur  at  the  locality  noted 
below. 

Length,  35  mm.  (restored);  width,  18  mm. 

Occurrence. — Aquia  Fokmation.  2 miles  below  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 


MAEYLAXD  GEOLOGICAL  SURVEA^ 


135 


Fuses  (?)  ixterstriatus  Heilprin. 

Plate  XXII,  Figs.  4,  4a. 

Fusus  interstriaUcs  Heilprin,  1880,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  xxxv,  pi.  xx, 
fig.  11. 

Description. — Shell  fusiform,  slender,  composed  of  about  ten  convex 
volutions,  the  first  three  of  which  are  smooth;  whorls  ornamented  with 
both  longitudinal  plications  and  revolving  lines,  the  last  of  which  (about 
eight  in  the  upper  whorls),  alternate  with  finer  intermediate  striae;  the 
longitudinal  plications  distinct  on  the  earlier  whorls,  but  becoming  much 
less  so  on  the  body  whorls,  and  the  one  preceding;  aperture  about  the 
length  of  the  spire;  the  canal  somewhat  tortuous;  outer  lip  thin,  den- 
tate within.’’  Heilprin,  1880. 

The  Maryland  form  differs  from  that  from  the  Gulf  states  in  that 
its  ribs  are  alternate,  while  in  the  latter  they  are  doubly  alternate  or 
with  three  smaller  ones  between  each  pair.  The  longitudinal  plications 
may  be  either  present  or  partly  absent  as  on  the  Gulf  form. 

Length,  16  mm.;  width,  6 mm. 

Occurrence. — Xaxjemoy  Foematiox.  Woodstock.  Aquia  Forma- 
Tiox.  1 mile  northeast  of  Piscataway,  Aquia  Creek. 

Collection. — Maryland  Geological  Survey. 

Family  MURICIDEA. 

Genus  TROPHON  Montfort. 

Trophox  subleyis  Harris. 

Plate  XXII,  Fig.  3. 

Trophon  sublevis  Harris,  1899,  Bull.  Amer.  Pal.,  No.  11,  p.  61,  pi.  viii,  figs.  1,  19. 

Description. — Size  and  general  form  as  indicated  by  the  figure; 
whorls  seven,  embryonic  three  smooth,  spire  and  body  whorl  smooth, 
polished,  but  with  nine  sharp-edged  costae  on  each  whorl,  becoming 
somewhat  pointed  on  the  shoulder;  faint  undulations  indicating  indis- 
tinct, distant  spirals  between  the  ribs;  outer  lip  thickened,  with  five 
crenulations  within,  the  upper  the  stronger;  no  umbilicus.”  Harris, 
1899. 


136 


SYSTEMATIC  PALEONTOLOGY 


A single  fragment  was  found  which  may  safely  he  assumed  to  repre- 
sent this  species. 

Lengthy  13  mm.  (restored);  width,  5 mm. 

Occurrence. — Aquia  Fokmation.  1 mile  northeast  of  Piscataway. 

Collection. — Maryland  Geological  Survey. 

Family  BUCCINIDAE. 

Genus  STREPSIDURA  Swainson. 

Steepsiduka  subscalaeina  Heilprin. 

Plate  XXII,  Figs.  5,  6,  7,  8,  8a. 

Fusus  (Strepsidura)  subscalarinus  Heilprin,  1880,  Proc.  Acad.  Nat.  Sci.  Pliila.,  vol. 

XXXV,  p.  372,  pi.  XX,  fig.  8. 

Fusus  {Strepsidura)  perlatus  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Fusus  {Strepsidura)  perlatus  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  67. 

Description. — Shell  somewhat  hncciniform,  whorls  about  eight,  snb- 
angular,  the  first  three  or  four  smooth,  the  remainder  ornamented  with 
both  longitudinal  costae  and  revolving  striae,  the  latter  showing  a ten- 
dency to  alternate  in  size;  the  costae  are  arcuate,  not  in  a regularly  con- 
tinnons  series,  those  of  the  body  whorl  extending  considerably  below 
the  middle  of  the  whorl;  aperture  about  the  length  of  spire,  the  canal 
somewhat  refiected;  columella  covered  with  a callous  deposit,  consider- 
ably twisted;  outer  lip  dentate  within.^^  Heilprin,  1880. 

Our  specimens  show  a marked  tendency  to  variation  both  in  shape 
and  sculpture,  as  the  figures  show,  but  none  of  the  forms  seem  to  be 
sufficiently  definite  to  warrant  the  separation  of  another  species. 

Occurrence. — Xanjemoy  Foemation.  Popes  Creek,  Woodstock. 
Aquia  Foemation.  Liverpool  Point,  Potomac  Creek,  2 miles  below 
Potomac  Creek,  Upper  Marlboro. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
Philadelphia  Academy  of  Xatural  Sciences. 

Genus  MELONGENA  Schumacher. 

MeLONGENA  (?)  POTOMACENSIS  n.  sp. 

Plate  XXII,  Fig.  9. 

Description. — Shell  fusiform,  showing  five  angulated  whorls  (the  api- 
cal whorls  and  portion  of  the  body  whorl  wanting);  with  about  twelve 


MARYLAND  GEOLOGICAL  SURVEY 


137 


longitudinal  costae,  vdiich  do  not  extend  above  the  shoulder;  ribs 
crossed  by  numerous  more  or  less  alternating  ridges,  of  which  two  on 
the  body  whorl,  about  half-way  between  the  shoulder  and  the  anterior 
end,  are  noticeably  larger  than  the  others;  finer  lines  of  growth  cross 
the  ridges  forming  a somewhat  rugose  sculpture;  above  the  shoulder 
smooth  with  a few  small  revolving  raised  lines  and  still  smaller  arcu- 
ated lines  of  groAvth. 

The  figured  specimen  is  the  only  one  known.  It  resembles  very 
closely  Melongena  sul)carinata  of  the  Paris  Basin  Eocene.  There  is  also 
a resemblance  to  Papillina  staminea  var.  Harris^  from  Claiborne,  Ala- 
bama. 

Length,  34  mm.;  width,  18  mm. 

Occuri'ence. — Aquia  Formation.  Potomac  Creek. 

Collection. — Philadelphia  Academy  of  Aatural  Sciences  (Ko.  6880  of 
the  Lea  Memorial  Collection). 

Genus  TUDICLA  Bolten. 

Tudicla  marylandica  n.  sp. 

Plate  XXIII,  Figs.  1,  la,  lb. 

Description. — Spire  flat,  concealed  except  on  top  by  the  body  whorl 
which  is  large,  much  expanded  above,  but  rapidly  contracting  below; 
surface  marked  by  lines  of  growth,  and  fine,  revolving  wrinkles  which 
become  strong  toward  the  beak;  periphery  of  body  whorl  with  spines  of 
moderate  size;  beaks  long,  narrow,  reflexed;  columella  twisted  obtusely. 

This  species  differs  from  P.  pyrula  Aid.  in  not  having  the  elevated 
spire  shown  in  Harris’  figure  of  a Midwayan  specimen,"*  and  also  in  not 
having  as  elevated  a spire,  as  ovate  a mouth,  nor  being  as  strongly 
spinose  as  the  Chickasawan  specimens. 

Length,  70  mm.;  width,  50  x 35  mm. 

Occurrence. — Aquia  Formation.  2 miles  below  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 


1 Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  xlviii,  1890,  p.  474,  pi.  xx,  fig.  2. 

2 Bull.  Amer.  Pal.,  vol.  iv,  pi.  xix,  fig.  2. 


138 


SYSTEMATIC  PALEONTOLOGY 


Tudicla  sp. 

Plate  XXIII,  Figs.  2,  2a. 

Fyropsis  (?)  sp.  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Pyropsis  sp.  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  67,  pi.  xi,  figs.  2a,  2b. 

{?)  Pyropsis  pyrula  Harris,  1899,  Bull.  Amer.  Pal.,  No.  11,  p.  46  (In  part). 

Desci'iption. — Several  casts  of  a large  Tudicla  have  been  found  at 
various  localities  in  the  Aqnia  formation.  They  differ  from  T.  mary- 
landica  in  having  a hluntly  angulated  shoulder.  We  have  not  seen  the 
casts  from  Fort  Washington  which  Professor  Harris  referred  to 
Py7'opsis  pyrula  hut  they  belong  probably  to  this  form. 

Length  (of  fragment),  40  mm.;  width,  55  mm. 

Occurrence. — Aquia  Fohmation.  Clifton  Beach,  Aquia  Creek, 
Crownsville,  Fort  Washington  (Harris). 

Collections. — Maryland  Geological  Survey,  Cornell  University. 

Tudicla  (?)  sp. 

Plate  XXIII,  Fig.  4;  Plate  XXIV,  Fig.  6. 

Description. — The  cast  of  a small  unknown  gastropod  is  very  abund- 
ant in  the  indurated  ledge  at  Aquia  Creek.  It  has  an  obtuse,  conic  spire, 
varying  in  height,  and  a body  whorl  much  expanded  at  the  top,  but 
diminishing  in  width  below.  The  beak  is  moderately  long,  straight  and 
slender.  The  spire  is  wound  on  or  slightly  below  the  shoulder  of  the 
whorl.  The  periphery  of  the  whorl  is  tuberculate. 

An  imperfect  shell  having  all  these  characters  was  also  found  at 
Popes  Creek.  It  has  a thick  shell  and  is  ornamented  with  distant, 
raised,  revolving  lines. 

Length,  40  (?)  mm.;  width,  27  mm. 

Occurrence. — Xanjemoy  Fokmation.  Popes  Creek.  Aquia  Fokma- 
TiON.  Aquia  Creek,  Clifton  Beach. 

Collections. — Johns  Hopkins  Universit}q  Maryland  Geological  Survey. 

Genus  LEVIFUSUS  Conrad. 

Levifusus  trabeatus  (?)  Conrad. 

Fusus  trabeatus  Conrad,  1833,  Fossil  Shells  of  the  Tertiary,  No.  3 [1st  Edit.],  p.  29. 

Fusus  trabeatus  Conrad,  1835,  Fossil  Shells  of  the  Tertiary,  No.  3 [2nd  Edit.],  p.  53, 
pi.  xviii,  fig.  1. 


MAKYLAXD  GEOLOGICAL  SUKTET 


139 


Fusiis  (Levifusus)  trabeatus  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 
(In  part.) 

Fusus  {Levifusus)  trabeatus  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  67.  (In 
part.) 

Description. — “ Shell  subfusiform,  ventricose,  with  revolving  elevated 
striae  at  the  base,  and  more  obscure  ones  on  the  spire : body  whorl  with 
two  distinct  rows  of  tubercles,  humeral  one  continued  on  the  spire.’’ 
Conrad,  1829. 

Several  fragments  of  molds  of  the  exterior,  as  well  as  less  clearly  de- 
fined casts  of  the  interior,  have  been  found.  They  cannot  be  identified 
with  L.  trabeatus  with  certainty.  The  casts  from  Aqnia  Creek  which 
were  formerly  identified  with  this  species  are  evidently  of  an  indetermi- 
nate Tudicla. 

Occurrence. — Naxjemoa^  Foematiox.  Popes  Creek. 

Collection. — Maryland  Geological  Survey. 

Levifusus  tkabeatus  (?)  var. 

Plate  XXIII,  Fig.  3. 

Description. — A single,  imperfect  specimen  was  found  at  Woodstock 
which  cannot  be  distinguished  in  its  present  condition  from  a Fulgur. 
It  would  be  unwise,  however,  to  assume  the  presence  of  that  genus  in 
the  Eocene  without  better  evidence  than  a single  cast.  The  specimen 
is  too  imperfect  for  description  but  a figure  is  given  and  the  form  tenta- 
tively referred  to  a variety  of  the  preceding  species.  The  substance  of 
the  shell  is  very  thin  and  apparently  smooth.  The  shoulder  is  carinate 
or  tuberculate.  The  suture  does  not  seem  to  be  channeled. 

Length,  73  mm.;  width,  25-40  mm.  (flattened). 

Occurrence. — Xaxjemoy  Foematiox.  Woodstock. 

Collection. — Maryland  Geological  Survey. 

Genus  METULA  Adams. 

Metula  maeylaxdica  n.  sp. 

Plate  XXIII,  Fig.  5. 

Description. — Shell  small,  elongate,  six-whorled;  sculpture  of  longitu- 
dinal folds  and  elevated  revolving  ribs;  body  whorl  with  thirteen  longi- 


140 


SYSTEMATIC  PALEONTOLOGY 


tiidinal  folds,  and  about  fifteen,  raised,  obtusely  rounded,  revolving  ribs 
becoming  alternate  toward  the  base;  other  whorls  with  six  ribs;  lines  of 
growth  fine  and  sharp;  onter  lip  with  ten,  irregnlarly  spaced  teeth;  canal 
short,  slightly  curved. 

Length,  11  mm.;  width,  5 mm. 

Occurrence. — Aquia  Fokmation.  2 miles  below  Potomac  Creek,  Po- 
tomac Creek,  1 mile  southeast  of  Mason  Springs. 

Collection. — Maryland  Geological  Survey. 

Genus  CHRYSODOMUS  Swainson, 

Chrysodomus  engonatus  (Heilprin). 

Plate  XXIII,  Pig.  6. 

Fusus  {Hemifusus?)  engonatus  Heilprin,  1880,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol. 

XXXV,  p.  372,  pi.  XX,  fig.  8. 

Descri'ption. — Shell  turreted,  of  about  ten  volutions,  the  first  three 
whorls  smooth  and  convex,  the  remainder  strongly  carinated,  and  trans- 
versed  by  numerous  fine  revolving  lines,  which  on  the  median  portion 
of  the  body  whorl  alternate  with  intermediate  finer  striae;  body  whorl 
impressed  immediately  below  the  carination  (shoulder  angulation);  lines 
of  growth  sinous,  and  approximating  the  characteristic  lines  of  the 
Pleurotomidae;  aperture  considerably  exceeding  the  spire  in  length; 
columella  slightly  arcuate,  and  presenting  a rudimentary  fold  at  about 
its  central  portion.’^  Heilprin,  1880. 

Length,  33  mm.;  width,  16  mm. 

Occurrence. — Aquia  Formation.  2 miles  below  Potomac  Creek,  Po- 
tomac Creek. 

Collections. — Maryland  Geological  Survey,  Philadelphia  Academy  of 
Natural  Sciences. 

Genus  PSEUDOLIVA  Swainson. 

Pseud  OLIVA  sp. 

Plate  XXIII,  Fig.  7. 

Description. — Only  internal  casts  of  this  form  have  been  found.  They 
are  not  unlike  in  size  and  shape  to  P.  venusta  (Conrad),  but  it  is  not 
safe  to  attempt  a specific  determination. 


MAEYLAXD  GEOLOGICAL  SUEYEA" 


141 


Length,  30  mm.;  Yndth,  17  mm. 

Occurrence. — Aquia  Foemation.  Upper  Marlboro,  Hardesty. 

Collection. — Maryland  Geological  Survey. 

Superfamily  TAENIOGLOSSA. 

Family  TRITONIDAE. 

Genus  TRITONIUM  Link. 

Teitonium  showalteei  (Conrad). 

Plate  XXIY,  Figs.  1,  la. 

Simpulu7n  showalteri  Conrad,  1860,  Jour.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  292, 
pi.  xlvii,  fig.  11. 

Description. — Fusiform;  whirls  eight,  angular,  periphery  of  angle 
acute,  situated  below  the  middle  of  the  vdiirl;  whirls  of  spire  costate 
longitudinally,  but  not  very  distinctly;  revolving  lines  closely  arranged, 
fine,  with  a few  distant  prominent  lines;  three  first  whirls  of  -the 
spire  smooth,  the  next  two  tnberculated;  angle  tnbercnlated;  a promi- 
nent, acute  line  on  the  body  whirl  runs  from  the  upper  extremity  of  the 
aperture,  and  a similar  finer  line  between  it  and  the  angle  above;  colum- 
ella rugose,  with  a prominent  fold  near  its  upper  end;  labium  dentate 
within.”  Conrad,  1860. 

Length,  26  mm.;  width,  13  mm. 

Occurrence. — Aquia  Foemation.  Month  of  Paspotansa  Creek,  2 
miles  below  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 

Family  DOLIIDAE. 

Genus  PYRULA  Lamarck. 

Pyeula  penita  vae.  Conrad. 

Plate  XXIV,  Fig.  2. 

Pyrula  penita  Conrad,  1833,  Fossil  Shells  of  the  Tertiary,  No.  3 [1st  Edit.],  p.  32. 

Pyrula  cancellata  Lea,  1833,  Contrib.  to  Geol.,  p.  154,  pi.  v,  fig.  160. 

Pyrula  elegantianma  Lea,  1833,  Contrib.  to  Geol.,  p.  155,  pi.  v,  fig.  161. 

Pyrula  tricarinata  Conrad,  1835,  Fossil  Shells  of  the  Tertiary,  No.  3 [2nd  Edit.], 
p.  38,  pi.  XV,  fig.  6. 

Description. — “ Shell  snbfnsiform,  reticulated,  with  three  carinations 
on  the  body  whorl:  striae  alternating  in  size:  five  volutions;  spire  ele- 
vated and  pointed.  Lip  thickened  toward  the  margin. 


142 


SYSTEMATIC  PALEONTOLOGY 


‘^Variety,  C.  Destitute  of  carinations,  and  probably  the  young  shell. 
Length  about  an  inch.”  Conrad,  1833. 

Several  specimens  have  been  found  which  are  very  close  to  this  species. 
They  are  nearer  the  Variety  C.  suggested  by  Conrad  and  named  P.  ele- 
gantissima  by  Lea. 

Length,  27  mm.;  width,  12  mm. 

Occurrence. — Nanjemoy  Foemation.  Popes  Creek. 

Collection. — Maryland  Geological  Survey. 

Pykula  (?)  sp. 

Plate  XXIV,  Fig.  5. 

Description. — Shell  thin;  body  whorl  large,  convex;  sculpture  of  nu- 
merous, closely  set,  revolving,  impressed  lines,  very  strongly  and  con- 
stantly punctate. 

Only  one  specimen  has  been  found  and  it  is  very  imperfect.  The 
spire  is  entirely  gone. 

Length  (of  fragment),  14  mm.;  width,  11  mm. 

Occurrence. — Xanjemoy  Foemation.  Popes  Creek. 

Collection. — Johns  Hopkins  University. 

Genus  FULGUROFICUS  Sacco. 

Fulgueoficus  aegutus  Clark. 

Plate  XXIV,  Figs.  3,  3a. 

Fulgur  argutus  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Fulgurojicus  argutus  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  68,  pi.  xii,  figs, 
la,  16. 

Fulgurojicus  triserialis  Harris,  1899,  Bull.  Amer,  Pal.,  No.  11,  p.  67,  pi.  viii,  fig.  17. 
(In  part.) 

Description. — Shell  moderately  short,  with  four  or  five  whorls;  first 
two  whorls  apparently  smooth;  third  whorl  with  faintly  impressed  spiral 
lines  and  minute  transverse  riblets;  later  whorls  with  spinous  tubercles 
at  the  shoulder;  body  whorl  also  with  two  lower  rows  of  tubercles  ar- 
ranged along  strongly  elevated  spiral  ridges  and  transversely  placed 
vertically  above  one  another;  ten  to  fourteen  tubercles  in  each  row;  nu- 
merous fine  spiral  threads  also  pass  over  the  spinous  ridges  and  inter- 


MAEYLAND  GEOLOGICAL  SUEVEA" 


143 


spaces;  lines  of  growth  somewhat  irregular;  canal  rather  long,  narrow/^ 
Clark,  1896. 

This  species  differs  from  F.  triserialis  Whitfield  in  having  the  three 
rows  of  tubercles  of  nearly  equal  strength,  and  spaced  at  nearly  equal 
distances,  in  having  more  elevated  spire,  and  in  having  that  portion  of 
the  body  whorl,  of  which  the  middle  row  of  tubercles  is  in  the  center, 
uniformly  convex  throughout,  instead  of  sharply  angulated  at  the 
shoulder  and  nearly  fiat  below. 

Length,  27  mm.;  width,  18  mm. 

Occurrence. — Nanjemoy  Foemation.  Woodstock.  Aquia  Foema- 
Tiox.  Potomac  Creek,  2 miles  below  Potomac  Creek,  Pomonkey  Neck, 
Upper  Marlboro. 

Collections. — Maryland  Geological  Survey,  U.  S.  National  Museum, 
Philadelphia  Academy  of  Natural  Sciences,  Johns  Hopkins  University. 


Genus  FUSOFICULA  Sacco. 

Fusoficula  juvexis  (Whitfield). 

Plate  XXIV,  Figs.  4,  4a. 

Pyrula  juvenis  Whitfield,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  259. 

Fusoficula  juvenis  Harris,  1899,  Bull.  Amer.  Pal.,  No.  11,  p.  66,  pi.  viii,  figs.  15,  16. 

Description. — Shell  small  and  fragile;  spire  elevated;  columella 
slender,  slightly  bent;  aperture  large,  elongate,  ovate  or  sub-elliptical; 
volutions  three;  marked  on  the  periphery  by  three  distinct  carinae  or  sub- 
angular  revolving  ridges,  the  upper  one  marked  with  closely  arranged, 
longitudinally  elongated  nodes,  the  others  simple;  entire  surface  marked 
by  very  fine  revolving  lines,  which  are  somewhat  fasciculate  below  the 
lower  Carina,  there  being  three  finer  ones  between  each  large  one.” 
Whitfield,  1865. 

A single  specimen  of  typical  form  and  excellent  state  of  preservation 
was  found. 

Length,  23  mm.;  width,  11  mm. 

Occurrence. — Aquia  Foematiox.  2 miles  below  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 


144 


SYSTEMATIC  PALEONTOLOGY 


Family  CASSIDIDAE. 

Genus  MO  RIO  Montfort. 

Morio  brevidentata  (Aldrich). 

Plate  XXIV,  Fig.  7. 

Cassidaria  hrevidentata  Aldrich,  1885,  Jour.  Cin.  Soc.  Nat.  Hist.,  p.  152,  pi.  iii,  fig.  20. 

Description. — Shell,  ohlong-oval,  whorls  seven;  suture,  channeled; 
surface  covered  with  fine  revolving  striae;  coarser,  distant  lines  upon  the 
body  whorl,  giving  the  shell  the  carinated  aspect  of  the  genus;  lines  of 
growth  fine,  a few  coarser  ones  showing  on  the  line  of  the  tubercles; 
apex,  smooth;  whorls  of  the  spire  carinate  and  slightly  tubercled;  a row 
of  upright  longitudinal  nodes  on  the  shoulder  of  the  body  whorl,  none 
below;  a single,  strong  varix  on  the  body  whorl;  aperture,  ovate;  inner 
lip  spreading  over  the  whorl,  with  three  plications  on  the  upper  part, 
smooth  in  the  central  part  and  plicate  below;  outer  lip  reflected,  plicate 
on  the  inner  edge  above  and  below,  smooth  in  the  center;  canal,  narrow, 
strongly  twisted.’^  Aldrich,  1885. 

Length,  30  mm.;  width,  20  mm. 

Occurrence. — Aquia  Formation.  1 mile  southeast  of  Mason  Springs, 
2 miles  below  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 

Family  CYPRAEIDAE. 

Genus  CYPRAEA  Linnl 
Cypraea  smithii  Aldrich. 

Plate  XXIV,  Fig.  8. 

Cypraea  smithii  Aldrich,  1886,  Geol.  Survey,  Ala.,  Bull.  1,  p.  33,  pi.  v,  fig.  3. 

Description. — Shell  oblong-ovate,  rather  flat,  surface  smooth;  labium 
crenulate  within,  smooth  on  the  base  and  flattened,  reflected  somewhat 
and  raised  above  base  of  shell;  aperture  slightly  crenulate  within,  ex- 
panded helow.’^  Aldrich,  1886. 

Fragments  of  a Cypraea  which  in  their  somewhat  imperfect  condition 
show  no  characters  which  would  prevent  their  being  referred  to  C. 
smithii  are  fairly  abundant  in  the  Potapaco  member,  hut  seem  to  he 
much  restricted  in  vertical  range. 


MAEYLAXD  GEOLOGICAL  SURVEY 


145 


Length,  18  mm.;  width,  15  by  8 mm.  (crushed). 

Occurrence. — Xaxjemoy"  Forwatiox.  West  of  Port  Tobacco,  mile 
below  Chapel  Point,  Head  of  Hanjemoy  Creek. 

Collection. — Maryland  Geological  Survey. 

Family  STROMBIDAE. 

Genus  CALYPTRAPHORUS  Conrad. 

Calyptraphorus  jacksoxi  Clark. 

Plate  XXV,  Figs.  1,  la,  2. 

CalypLrophorm  jacksoni  Clark,  1895,  .Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Calyptrophorus  jacksoni  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  68,  pi.  xii, 
figs.  2a,  26. 

Description. — Shell  large,  solid,  many  whorled;  spire  prolonged,  acu- 
minate; surface  of  adult  covered  with  thick,  calcareous  deposit,  entirely 
enveloping  the  whorls;  inner  lip  thickened  with  extensive  callosity.” 
Clark,  1896. 

This  very  remarkable  form  is  quite  distinct  from  any  other  species,  but 
some  of  the  Gulf  types  ajjproach  it  in  size  and  amount  of  callosity. 
Some  of  the  largest  specimens  of  C.  trinodiferus  Conrad  show  certain 
points  of  similarity,  but  the  Maryland  species  cannot  be  confounded 
with  it.  In  the  absence  of  young  shells,  the  character  of  the  surface 
decoration  is  unknown.  A large  number  of  specimens  have  been  found 
in  the  South  Eiver  area. 

Length  (restored),  102  mm.;  width,  44  mm. 

Occurrence. — Aquia  Forwatiox.  South  Eiver,  Upper  Marlboro. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
Museum  of  Comparative  Zoology. 

Calyptraphorus  trixodiferus  Conrad. 

Plate  XXV,  Fig.  3. 

Calyptraphorus  trinodif eru.'i  Conrad,  1857,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  ix, 

p.  166. 

Calyptraphorus  trinodiferus  Conrad,  I860,  Jour.  Acad.  Nat.  Sci.  Pbila.,  2nd  ser., 
vol.  iv,  pi.  xlvii,  fig.  29. 

Description. — Subfusiform,  with  three  distinct  nodes  on  the  upper 

part  of  the  body  volution;  spire  subtriangular,  having  curved  longitu- 
10 


146 


SYSTEMATIC  PALEONTOLOGY 


dinal  ribs  visible  beneath  the  tnnic;  rostrum  of  the  spire  elongated  and 
curved;  labrnm  with  a prominent  angle  above/^  Conrad,  1857. 

Length,  45  mm.;  width,  18  mm. 

Occurrence. — ^^anjemoy  Foemation.  Potomac  Creek  (Zone  11). 
Aquia  Foemation.  2 miles  below  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 

CaLYPTEAPHOEUS  TEINODIFEEUS  (?)  VAE. 

Plate  XXV,  Figs.  4,  4a. 

Description. — This  form  has  the  prolonged  spire  and  longitudinal  rib- 
bing of  C.  trinodiferus,  differing  from  it  only  in  lacking  the  nodes.  It 
might  perhaps  be  referred  to  a variety  of  C.  velatus,  but  the  characters 
which  separate  it  from  C.  velatus  seem  less  likely  to  be  accidental  than 
those  separating  it  from  C.  trinodiferus.  In  the  Philadelphia  Academy 
of  Xatnral  Sciences  are  a few  specimens  of  C.  velatus  which  have  the 
prolonged  spire  of  this  form,  but  none  have  the  ribbing  on  the  spire. 

Length,  46  mm.;  width,  15  mm. 

Occurrence. — Xanjemoy  Foemation.  Popes  Creek.  Aquia  Foema- 
tion. 1 mile  southeast  of  Mason  Springs. 

Collection. — Maryland  Geological  Survey. 

Family  APORRHAIDAE. 

Genus  APORRHAIS  da  Costa. 

Apoeehais  potomacensis  n.  sp. 

Plate  XXV,  Figs.  5,  6. 

Description. — Shell  fusiform;  spire  elevated,  pointed;  body  whorl 
large;  outer  lip  much  expanded;  digitations,  two,  slender  and  long;  pos- 
terior digitation  about  twice  as  long  as  the  anterior;  callus  on  the  inner 
lip  thick;  whorls  strongly  convex  and  somewhat  angnlated  below  the 
middle;  body  whorl  with  two  obtuse  revolving  ribs,  which  extend  down 
the  middle  of  the  digitations,  and  disappear  in  the  opposite  direction 
beneath  the  callus  on  the  labium;  about  twenty  longitudinal  ribs  on 
each  whorl,  with  a deep  curve  below  the  suture,  overridden  by  fine, 
raised,  close-set,  revolving  lines. 


MAEYLAXD  GEOLOGICAL  SUKVEY 


147 


Length,  25  mm.;  width  (of  body  whorl),  10  mm.;  length  of  posterior 
digitation,  22  mm. 

Occurrence. — Aquia  Fokmatiox.  1 mile  northeast  of  Piscataway, 
Paspotansa  Creek,  2 fliiles  below  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 

Family  TURRITELLIDAE. 

Genus  TURRITELLA  Lamarck. 

Tueeitella  moetoxi  Conrad. 

Plate  XXVI,  Figs.  1-5. 

Turritella  mortoni  Conrad,  1830,  Jour.  Acad.  Nat.  Sci.  Pliila.,  vol.  vi,  p.  221,  pi.  x, 
flg.  2. 

Turritella  mortoni  Conrad,  1832,  Fossil  Shells  of  the  Tertiary,  No.  3 [2nd  Edit.], 
p.  40,  pi.  XV,  flg.  11. 

Turritella  mortoni  Morton,  1834,  Synopsis  Organ.  Rem.  Cretaceous  Group,  App., 

p.  4. 

Turritella  mortoni  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  107. 

Turritella  mortoni  Conrad,  1865,  Amer.  Jour.  Conch.,  voL  i,  p.  32. 

Turritella  mortoni  de  Gregorio,  1^0,  Ann.  Geol.  et  Pal.,  p.  122,  pi.  xi,  flg.  7. 

Turritella  mortoni  var.  postmortoni  Harris,  1894,  Amer.  Jour.  Sci.,  ser.  iii,  vol.  xlvii, 
p.  303,  flirs.  1,  2,  3. 

Turritella  mortoni  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Turritella  mortoni  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  69,  pi.  xiii,  flgs. 
la-le. 

Turritella  mortoni  Harris,  1899,  Bull.  Amer.  Pal.,  No.  11,  p.  74,  pi.  x,  flgs.  3,  4. 

Description. — Shell  turreted,  conical,  thick,  with  revolving  distant, 
and  finer  intervening  striae;  whorls  with  an  elevated  acute  carina  near 
the  base  of  each;  volutions  about  eleven;  the  striae  are  largest  on  the 
elevations  of  the  whorls,  which  are  slightly  concave  above,  and  abruptly 
terminate  at  the  sutures;  the  lines  of  growth  on  the  last  whorl  are  strong 
and  much  undulated.^'  Conrad,  1830. 

This  important  species  was  one  of  the  first  to  be  recognized  in  the 
Maryland  Eocene,  and  has  been  generally  regarded  as  one  of  the  most 
characteristic,  as  it  is  one  of  the  most  common  forms.  At  times  it 
makes  up  whole  beds,  as  shown  in  the  Paspotansa  member  of  the  Aquia 
formation  at  Aquia  Creek,  Potomac  Creek,  and  other  neighboring  lo- 
calities. 

Turritella  mortoni  shows  very  great  variations  in  the  form  and  deco 


148 


SYSTEMATIC  PALEONTOLOGY 


ration  of  the  whorls,  and  if  it  were  not  for  the  great  number  of  inter- 
mediate types  one  might  readily,  establish  several  independent  species. 

Some  specimens  have  nearly  equally  rounded  whorls  with  evenly 
spaced  spiral  lines,  while  others  are  prominently*carinated  toward  the 
base  of  the  whorl  and  the  spiral  threads  are  irregularly  spaced,  varying 
in  prominence  and  number. 

A variety  named  postmortoni  by  Harris  is  characterized  by  its  rather 
smaller  size,  plainer  surface,  and  extremely  sharp  basal  carina.  Figure 
5 represents  this  form. 

Length,  130  mm.;  width,  33  mm. 

Occurrence. — Aquia  Formation.  Fort  Washington,  1 mile  northeast 
of  Piscataway,  Northwest  of  Piscataway  (W.  of  Tinkers  Cr.),  Brooks  Es- 
tate near  Seat  Pleasant,  Glymont,  Liverpool  Point,  Clifton  Beach,  1 
mile  southeast  of  Mason  Springs,  Aquia  Creek,  Potomac  Creek,  Upper 
Marlboro,  Sheckels  Farm  near  South  Eiver,  1 mile  west  of  Hardesty, 
Eolph’s  Landing. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
U.  S.  National  Museum,  Philadelphia  Academy  of  Natural  Sciences. 

Turritella  humerosa  Conrad. 

Plate  XXVII,  Figs.  1,  la. 

Turritella  humerosa  Conrad,  1835,  Trans.  Geol.  Soc.,  Penn.,  p.  340,  pi.  xiii,  fig.  3. 

Turritella  humerosa  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.,  Phila.,  vol.  iv,  p.  107. 

Turritella  humerosa  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  32. 

Turritella  humerosa  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  11. 

Txirritella  Immerosa  Harris,  1894,  Amer.  Jour.  Sci.,  ser.  iii,  vol.  xlvii,  p.  303. 

Turritella  humerosa  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Turritella  humerosa  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  70,  pi.  xiv,  fig.  1. 

Turritella  Immerosa  Harris,  1899,  Bull.  Amer.  Pal.,  No.  11,  p.  75,  figs.  5,  6,  7. 

Description. — Shell  turreted^  subulate;  whorls  with  fine  regular  re- 
volving striae;  an  obtuse  slight  elevation  on  the  summit,  a shallow 
groove  at  the  base  of  each.^’  Conrad,  1835. 

Turritella  humerosa,  although  not  an  uncommon  species,  is  far  less 
frequent  than  T.  mortoni.  It  is  very  readily  separated  from  the  latter 
by  its  flat  whorls  and  prominent  siihsutural  carina,  which  makes  the 
whorls  of  nearly  equal  diameter  above  and  below. 


MARYLAND  GEOLOGICAL  SURVEY 


149 


This  species  apparently  never  reaches  the  dimensions  of  T.  mortoni, 
hnt  is  commonly  associated  with  it.  Like  T.  mortoni,  it  is  largely  con- 
fined to  the  Paspotansa  member  of  the  Aqnia  Formation. 

Length,  140  mm.;  width,  25  mm. 

Occurrence. — Aquia  Formation.  Fort  Washington,  Clifton  Beach, 
Aqnia  Creek,  1 mile  southeast  of  Mason  Springs,  Glymont,  Month  of 
Paspotansa  Creek,  1 mile  northeast  of  Piscataway,  Near  Annapolis,  Be- 
tween Bnena  Vista  and  Collington,  Tinkers  Creek,  Liverpool  Point, 
Tapper  Marlboro,  Sheckels  Farm  near  South  Eiver,  Brooks  Estate  near 
Seat  Pleasant. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
L^.  S.  National  Mnsenm,  Philadelphia  Academy  of  Natural  Sciences. 

Turritella  potomacensis  n.  sp. 

Plate  XXVII,  Figs.  2,  3. 

Description. — Shell  slender,  elongate;  whorls  many;  each  whorl  cari- 
nated  at  the  base,  diminishing  sharply  in  diameter  toward  the  apex,  and 
concave  in  the  middle;  sculpture  consisting  of  one  or  two  strong,  ele- 
vated carinae  at  the  base  of  the  whorl,  and  about  five  moderately  strong 
ones,  irregularly  spaced  above  them,  and  between  these  secondary  alter- 
nating threads  and  fine,  raised,  revolving  lines;  some  of  the  carinae, 
especially  those  toward  the  middle  of  the  whorl,  are  headed. 

Length,  45  mm.;  width,  10  mm. 

Occurrence. — Nanjemoy  Formation.  Popes  Creek,  Woodstock. 

Collection. — Maryland  Geological  Survey. 

Genus  MESALIA  Gray. 

Mesalia  obruta  (Conrad). 

Plate  XXVII,  Fig.  4. 

Turritella  obruta  Conrad,  1833,  Fossil  Shells  of  the  Tertiary,  No.  4,  p.  4.5  ; No.  3 
[2nd  Edit.],  1835,  p.  40.  pi.  xv,  ti^^.  12. 

Turritella  venusta  Conrad,  1835,  Trans.  Geol.  Soc.,  Penn.,  vol.  i,  p.  336. 

Description. — Snhnlate,  with  ahont  eleven  slightly  convex  volutions, 
with  about  seven  sharp  elevated  striae  on  each,  and  intermediate  fine 
crowded  lines;  space  about  the  suture  indented.’’  Conrad,  1833. 


150 


SYSTEMATIC  PALEONTOLOGY 


This  form  is  very  abundant  in  the  IsTanjemoy  formation,  and  occurs 
near  the  top  of  the  A quia  formation  at  Upper  Alarlboro,  in  the  indurated 
ledge  and  just  above  it,  and  also  in  the  same  bed  near  South  Eiver  bridge. 

Length,  30  mm.;  width,  10  mm. 

Occurrence. — Nanjemoa"  Formation.  Popes  Creek,  Woodstock. 
Aquia  Formation.  Upper  Marlboro,  Sheckels  Farm  near  South  Eiver. 

Collectio7i. — Maryland  Geological  Survey. 

Family  VERMETIDAE. 

Genus  VERMETUS  Adams. 

Vermetus  sp. 

Plate  XXVII,  Figs.  5,  5a,  6,  7. 

Vermetus  sp.  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Vermetus  sp.  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  71,  pi.  xiv,  figs.  2a,  2b. 

Description. — Fragmentary  masses  of  this  form  are  found  at  various 
points  in  the  Potomac  Eiver  region,  but  no  specimen  sufficiently  well 
preserved  for  specific  determination  has  been  obtained.  The  fragments, 
however,  probably  represent  a new  species.  The  form  is  characterized 
by  longitudinal  furrows,  giving  it  a somewhat  angulated  appearance,  and 
by  transverse,  scaly  lines  interrupted  by  the  furrows.  The  average 
diameter  of  the  tubes  is  about  2 mm. 

Occurrence. — Aquia  Formation.  Piscataway  Creek,  Potomac  Creek, 
Eolph’s  Landing,  Upper  Marlboro. 

Collections. — U.  S.  Xational  Museum,  Johns  Hopkins  University, 
Maryland  Geological  Survey. 

Family  NATICIDAE. 

Genus  NATICA  Lamarck, 

Natica  cliftonensis  Clark. 

Plate  XXVIII,  Fig.  1. 

Natica  cliftonensis  Clark,  1895,  Jolms  Hopkius  Univ.  Circ.,  vol.  xv,  p.  4. 

Natica  cliftonensis  Clark,  1890,  Bull.  141,  U.  S.  Geol.  Survey,  p.  69,  pi.  xii,  fig.  4. 

Description. — “ Shell  small,  with  four  or  five  whorls;  spire  low;  body 
whorl  much  inflated;  suture  well  marked;  surface  smooth,  except  for 
lines  of  growth;  aperture  large,  with  thick  callus.”  Clark,  1896. 


MARYLAND  GEOLOGICAL  SURVEY 


151 


In  addition  to  the  type  we  have  only  a crnshed  Natica  from  Wood- 
stock  that  may  represent  this  species. 

Length,  10  mm.;  wddth  12  mm. 

Occurrence. — Xaxjemoy  Formation.  Woodstock.  (?)  Aquia  For- 
mation. Clifton  Beach. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University. 

Genus  LUNATIA  Gray. 

Lunatia  marylandica  Conrad. 

Plate  XXVIII,  Figs.  2,  2a,  3. 

Lunatia  marylandica  Conrad,  186.'5,  Amer.  Jour.  Conch.,  vol.  i.  pp.  26,  211,  pi.  xxi, 
fig.  11. 

Lunatia  marylandica  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Lunatia  marylandica  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  69,  pi.  xii,  figs 
3a— 3c. 

cf.  Natica  eminula  var.  Harris,  1899,  Bull.  Amer.  Pal.,  No.  11,  p.  88,  pi.  xi,  fig.  22. 

Description. — Snhorbicnlar  or  snbovate,  volutions  5;  spire  short, 
whorls  convex,  subcontracted  below  the  suture;  labium  with  a callus  on 
the  upper  part,  reflected  over  the  umbilical  margin;  umbilicus  moderate 
in  outline,  profound,  showing  most  of  the  volutions.’^  Conrad,  1865. 

The  stratigraphic  and  geographic  range  of  this  species  is  very  great. 
It  is  larger,  however,  and  more  abundant  in  the  lower  beds  of  the  Aquia 
formation.  The  afflnities  of  the  species  are  with  L.  eminula  (Conrad) 
of  Alabama,  especially  with  L.  eminula  var.  Harris,  of  the  Alabama 
Chickasawan,  which  is  an  intermediate  member  of  a series  of  which  the 
Claibornian  L.  eminula  and  L.  marylandica  are  end  members. 

The  separation  of  these  species  is  very  difficult,  and  possibly  all  the 
forms  ought  to  be  referred  to  L.  eminula  which  is  the  older  name.  The 
Maryland  forms  show  almost,  if  not  quite,  the  complete  range  of  varia- 
tion of  the  series. 

Length,  32  mm.;  width,  30  mm. 

Occurrence. — Xanjemoy  Formation.  East  and  west  of  Port  Tobacco, 
Woodstock.  Aquia  Formation.  1 mile  northeast  of  Piscataway,  Po- 
tomac Creek,  2 miles  below  Potomac  Creek,  Upper  Marlboro,  Liverpool 
Point,  Mouth  of  Paspotansa  Creek,  Aquia  Creek,  1 mile  southeast  of 
Mason  Springs,  Glymont,  Hardesty,  Fort  AVashington. 


152 


SYSTEMATIC  PALEONTOLOGY" 


Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
U.  S.  National  Museum,  Philadelphia  Academy  of  Natural  Sciences. 

Family  CAPULIDAE. 

Genus  CALYPTRAEA  Lamarck, 

Cala"ptkaea  aperta  (Solander). 

Plate  XXVIII,  Pigs.  4,  5. 

Trochus  apertus  Solander,  1766,  Foss.  Haut.,  p.  9,  figs.  1,  2. 

Calyptraea  trochiformis  Lamarck,  1804,  Ann.  Mns.  d’Hist.  Nat.,  vol.  i,  p.  1.5,  fig.  3. 

Calyptraea  trochiformis  Clark,  1895,  Jolms  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Calyptraea  trochiformis  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  70. 

Calyptraea  aperta  Harris,  1899,  Bull.  Aiuer.  Pal.,  No.  11,  p.  84,  pi.  xi,  figs.  18-16. 

Description. — Shell  orbicular,  thin,  obtusely  conical;  volutions  three 
or  four;  apex  suhcentral;  later  whorls  spinose;  whole  surface  (except 
protoconch)  roughened  with  irregular,  wavy  lines  of  growth,  or  a vermi- 
cular shagreening;  septum  slightly  concave;  pillar  reflected,  giving  the 
appearance  of  an  umbilicus. 

This  species  is  represented,  usually  in  a poorly  preserved  state,  in 
nearly  all  the  beds  and  localities  of  the  Maryland  Eocene.  The  largest 
specimens  are  in  the  Aquia  formation. 

Length,  15  mm.;  width,  28  mm. 

Occurrence. — Nan.jemoa"  Formation.  Popes  Creek,  Woodstock,  East 
and  west  of  Port  Tobacco,  \ mile  below  Chapel  Point.  Aquia  Forma- 
tion. Fort  IVashington,  Glymont,  Clifton  Beach,  Liverpool  Point,  Up- 
per Marlboro,  Aquia  Creek,  Potomac  Creek,  2 miles  below  Potomac 
Creek,  1 mile  southeast  of  Mason  Springs. 

Collection. — Maryland  Geological  Survey. 

Family  LITTORINIDAE. 

Genus  LITIOPA  Rang. 

Litiopa  marylandica  n.  sp. 

Plate  XXVIII,  Figs.  6,  6a. 

Description. — Shell  thin,  with  six  whorls;  the  first  two  whorls  smooth^ 
the  third  with  fine,  closely-set,  revolving  striations  from  suture  to  su- 


MARYLAND  GEOLOGICAL  SURVEY 


153 


tiire,  the  fourth  with  striations  on  the  upper  half,  the  lower  half  being 
smooth,  the  fifth  and  sixth  (body)  whorls  smooth,  except  for  very  faint, 
revolving  lines,  which  are  less  distinct  than  the  lines  of  growth,  and 
about  eight,  sharp,  revolving  lines  around  the  umbilicus;  callosity  on 
the  labium  thin;  umbilicus  moderate;  mouth  large;  columella  concave 
above. 

Length,  8 mm.;  width,  4 mm. 

Occurrence. — Aquia  Formation.  2 miles  below  Potomac  Creek. 

Collection. — ]\Iaryland  Geological  Survey. 

Superfamily  PTENOGLOSSA. 

Family  SOLARllDAE. 

Genus  SOLARIUM  Lamarck. 

Solarium  sp. 

Plate  XXVIII,  Figs.  7,  7a. 

Solarium  sp.  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Solarium  sp.  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  71,  pi.  xiv,  tigs.  4«,  46. 

Xo  new  material  belonging  to  this  genus  has  been  obtained  except  an 
indeterminate  fragment  from  near  Mason  Springs.  Xeither  this,  nor 
the  cast  from  Aquia  Creek,  give  any  clew  to  the  specific  characters. 

Length,  6 mm.;  width,  16  mm. 

Occurrence. — Aquia  Formation.  Aquia  Creek,  1 mile  southeast  of 
Mason  Springs. 

Collection. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

Family  SCALARllDAE. 

Genus  SCALA  Klein. 

ScALA  viRGiNiANA  Clark. 

Plate  XXVIII,  Figs.  8,  8a,  9,  9a. 

Scala  virginiana  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Scala  virginiana  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  71,  pi.  xiv,  ligs.  3a,  36. 

Description. — Shell  probably  seven-  or  eight-whorled;  surface  cov- 
ered with  a uniform,  fine,  spiral  striation;  varices  fifteen  to  the  whorl. 


154 


SYSTEMATIC  PALEONTOLOGY 


inflected  forward  and  prominent;  some  of  the  varices  are  more  promi- 
nent than  others,  and  in  a few  instances  are  partially  divided  by  a 
central  groove;  aperture  nearly  round/^  Clark,  1896. 

Some  specimens  show  a large  umbilicus,  in  others  it  is  absent. 

Length,  22  mm.;  width,  14  mm. 

Occurrence. — Aquia  Fokmation.  Aquia  Creek,  Potomac  Creek. 

Collection. — U.  S.  National  Museum,  Philadelphia  Academy  of  Natural 
Sciences. 

SCALA  POTOMACENSIS  n.  Sp. 

Plate  XXVIII,  Fig.  10. 

Description. — Shell  elongate,  moderately  slender,  eight-whorled; 
mouth  round;  base  with  numerous,  closely-set,  revolving  lines  and  folds 
radiating  to  the  varices;  whorls  closely-set;  moderately  and  uniformly 
convex;  varices  low,  obtuse,  twenty-five  on  the  body  whorl,  and  about  as 
many  on  the  whorls  of  the  spire,  stronger  than  ordinary,  and  occurring 
at  irregular  intervals;  raised  revolving  threads,  about  30  in  number, 
alternating  and  doubly  alternating  in  strength,  run  between  without 
crossing  the  varices. 

Length,  20  mm.;  width,  8 mm. 

Occurrence. — Aquia  Formation.  2 miles  below  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 

ScALA  SESSiLis  Conrad. 

Plate  XXVIII,  Fig.  11. 

Scala  sessilis  Conrad,  1833,  Fossil  Shells  of  the  Tertiary,  No.  4,  p.  45. 

Description. — Subulate,  with  rather  thick  longitudinal  costae,  and 
minute  crowded  spiral  lines;  whorls  nine,  sessile  or  contiguous;  base  of 
the  body  whorl  carinated.’^  Conrad,  1833. 

Occurrence. — Aquia  Formation.  2 miles  below  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 

Scala  carinata  Lea. 

Plate  XXVIII,  Fig.  12. 

Scala  carinata  Lea,  1833,  Contrib.  to  Geol.,  p.  116,  pi.  iv,  fig,  103. 

Description. — “ Shell  conical,  closely  ribbed,  carinate  on  the  inferior 
part  of  the  last  whorl;  substance  of  the  shell  thick;  spire  elevated. 


MAKYLAND  GEOLOGICAL  SUKVEY 


155 


pointed;  ribs  about  twelve,  lamelliform;  whorls  six,  rounded;  mouth 
roimd/^  Lea,  1833. 

Occurrence. — Aquia  Fokmation.  2 miles  below  Potomac  Creek,  Up- 
per Marlboro. 

Collection. — Maryland  Geological  Survey. 

Superfamily  GYMNOGLOSSA. 

Family  PYRAMIDELLIDAE. 

Genus  TURBONILLA  Risso. 

Subgenus  PYRGISCUS  Philippi. 

Tukbonilla  potomacensis  n.  sp. 

Plate  XXIX,  Fig.  1. 

Description. — Shell  stout;  whorls  eight,  moderately  convex;  about 
twenty-five  slightly  curved,  longitudinal  ribs  on  the  body  whorl,  crossed 
by  eight,  impressed,  revolving  lines,  which  are  deepest  between  the  ribs; 
base  of  shell  with  impressed,  revolving  lines,  and  faint,  radiating  ribs; 
mouth  ovate. 

Length,  10  mm.;  width,  4 mm. 

Occurrence. — Aquia  Formation.  Potomac  Creek,  2 miles  below  Po- 
tomac Creek. 

Collection. — Maryland  Geological  Survey. 

Genus  TUBA  Lea. 

Tuba  marylandica  n.  sp. 

Plate  XXIX,  Fig.  2. 

Description. — Shell  elongate;  whorls  seven,  strongly  convex,  covered 
with  eight  raised  revolving  threads,  with  narrower  interspaces;  threads 
strongly  beaded  by  intersections  with  raised  longitudinal  lines. 

Length,  12  mm.;  width,  5 mm. 

Occurrence. — Nanjemoy  Formation.  Popes  Creek.  Aquia  Forma- 
tion. Mouth  of  Paspotansa  Creek,  1 mile  southeast  of  Mason  Springs. 

Collection. — Maryland  Geological  Survey. 


15G 


SYSTEMATIC  PALEONTOLOGY 


Genus  ODOSTOMIA  Fleming. 

Odostomia  tkapaquaka  (Harris). 

Plate  XXIX,  Fig.  3. 

Syryiola  irapaquara  Harris,  1895,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  xlvii,  p.  77,  pi.  viii, 
tig.  10. 

Description. — Size  and  general  form  as  indicated  by  the  figure; 
whorls  7;  1 small,  sinistral;  2-7  polished,  slightly  tnmid,  with  a well- 
marked  suture;  aperture  moderate,  striate  within;  one  strong  plait  on 
the  columella.’’  Harris,  1895. 

This  species  has  some  resemblance  to  the  figure  of  Acteon  melanellus 
Lea,  but  it  tapers  more  gradually,  has  shorter  whorls,  stronger  lines  of 
growth  and  no  revolving  lines  (or  almost  none),  while  they  are  strong  in 
A.  melanellus. 

Our  specimens  are  very  different  from  the  Chickasawan  form — 0.  in- 
significa  Aldrich,  which  Harris  regards  as  a synonym  of  0.  trapaquara. 

Length,  7 mm.;  width,  2.5  mm. 

Occurrence. — Aquia  Fokmation.  Potomac  Creek,  2 miles  below  Po- 
tomac Creek,  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Family  EULIMIDAE. 

Genus  NISO  Risso. 

XlSO  UMBILICATA  (Lea). 

Plate  XXIX,  Fig.  4. 

Pasithea  umbilicata  Lea,  1833,  Contrib.  to  Geol.,  p.  103,  pi.  iv,  tig.  85. 

Description. — Shell  elevated  above,  rounded  below,  subcarinate,  pol- 
ished; substance  of  the  shell  thin;  apex  acute;  suture  linear;  umbilicus 
large;  Avhorls  nine,  flattened;  mouth  subovate,  acutely  angular  above, 
one-fifth  the  length  of  the  shell;  columella  incurved  at  base;  margin  en- 
tire. ...  Its  umbilicus  is  wide,  with  a large  spiral  groove.  On  some 
of  the  wliorls  the  line  of  growth  may  be  indistinctly  seen.”  Lea,  1833. 

Length,  24  mm.;  width,  5 mm. 

Occurrence. — Aquia  Formation.  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 


MARYLAND  GEOLOGICAL  SURVEY 


157 


Order  ASPIDOBRANCHIATA. 

Suborder  RHIPIDOGLOSSA. 

Family  TROCHIDAE. 

Genus  GIBBULA  Risso. 

Gibbula  glandula  (Conrad). 

Plate  XXIX,  Fig.  5. 

2fonodonta  glandula  Conrad,  1830,  Jour.  Acad.  Nat.  Sci.  Phila.,  vol.  vi,  pp.  214,  220, 
pi.  ix,  fig.  15. 

Monodonta  glandula  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  102. 

2Ionodonta  glandula  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  11. 

Gihhula  glandula  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Gibbula  glandula  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  72,  pi.  xiv,  fig.  5. 

Description. — “ Shell  conical,  with  about  four  convex  volutions;  re- 
volving striae  fine,  crowded  and  wrinkled;  suture  deeply  impressed;  right 
lip  toothed  within  at  the  base;  margin  entire. 

The  teeth  or  tubercles  extend  to  the  base  of  the  columella  of  this 
shell.’^  Conrad,  1830. 

Length,  8 mm.;  width,  7 mm. 

Occurrence. — Aquia  Formation.  Piscataway  (Conrad),  Potomac 
Creek,  Upper  Marlboro. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey, 
Philadelphia  Academy  of  Xatural  Sciences. 

Genus  CALLIOSTOMA  Swainson. 

Calliostoma  sp. 

Description. — Two  specimens  of  Calliostoma,  both  too  imperfect  either 
to  figure  or  to  describe,  were  found  in  the  Aquia  formation.  The  one 
from  below  Potomac  Creek  is  part  of  the  base  of  the  body  whorl.  It 
shows  a strong  basal  carina,  and  revolving  threads  of  various  size,  all 
slightly  granulate.  The  fragment  from  Upper  Marlboro  does  not  show 
the  surface  decoration,  hut  has  a deep  groove  in  the  middle  of  the  whorl. 

Occurrence. — Aquia  Formation.  Upper  Marlboro,  2 miles  below  Po- 
tomac Creek. 

Collection. — Maryland  Geological  Survey. 


158 


SYSTEMATIC  PALEONTOLOGY 


Family  FISSURELLIDAE. 

Genus  FISSURIDEA  Swainson. 

Fissukidea  maklboroensis  n.  sp. 

Plate  XXIX,  Figs.  6,  6a. 

Description. — Shell  ovate,  depressed;  apex  anteriorly  situated,  acute; 
foramen  keyhole-shaped,  anterior  to  the  apex,  plane  sloping  forward; 
internal  callus  shaped  like  the  end  of  a gun-stock,  deeply  dinted  behind; 
surface  sculptured  by  fine,  impressed,  radiating  lines,  with  broad  and 
fiat  interspaces  toward  the  periphery,  raised  and  rounded  toward  the 
apex;  interspaces  doubly  alternating  in  width  or  height,  every  fourth 
being  much  wider,  while  of  each  group  of  intervening  narrower  ones 
that  in  the  middle  is  slightly  wider  than  the  rest;  alternation  becomes 
simple  on  the  posterior  slope,  with  double  alternation  strongest  on  the 
anterior  slope. 

Length,  17.5  mm.;  width,  12  mm.;  height,  6 mm. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Class  SCAPHOPODA. 

Order  SOLENOCONCHIA. 

Family  DENTALllDAE. 

Genus  DENTALIUM  Linnk 
Dentalium  minutistriatum  Gabb. 

Plate  XXIX,  Fig.  7. 

Dentalium  minutistriatum  Gabb,  1860,  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  Ser.,  vol. 
iv,  p.  386,  pi.  Ixvii,  tig.  46. 

Description. — ^^Very  slightly  curved,  marked  by  numerous  small  lon- 
gitudinal ribs,  all  of  the  same  size,  no  trace  of  alternation;  aperture 
round.^’  Gabb,  1860. 

This  form  differs  from  D.  mississippiensis  in  having  finer,  non-alter- 
nate ribbing,  and  not  attaining  to  so  great  a size. 


MAKYLAXD  GEOLOGICAL  SURVEY 


159 


The  figured  specimen  (besides  which  only  fragments  have  been  found) 
is  strongly  and  regularly  compressed  in  the  plane  at  right  angles  to  that 
of  curvature.  So  natural  does  the  compression  appear  that  the  indi- 
vidual was  referred  to  the  genus  Compressidens  of  Pilshry.  But  other 
fragments  have  been  found  which  have  a perfectly  round  aperture,  and 
faint  cracks  have  been  discovered  along  the  lines  of  greatest  curvature 
of  the  compressed  specimen,  and  therefore  the  character  must  probably 
be  regarded  as  accidental. 

Length,  17  mm.;  width,  1.75x2.5  mm.  (flattened). 

Occurrence. — Naxjemoy  Formation.  Popes  Creek. 

Collection. — Maryland  Geological  Survey. 

Dentalium  mississippiensis  Conrad. 

Plate  XXIX,  Fig.  8. 

Dentalium  misHssippiensis  Conrad,  1848,  Jour.  Acad.  Nat.  Sci.  Phila.,  3ud  Ser.,  vol. 
i,  p.  113,  pi.  xi,  fig.  1. 

Description. — Curved,  attenuated  above,  longitudinally  striated,  the 
lines  alternating  in  size.  ...  It  differs  from  D.  tlialloides  in  having 
more  numerous  and  much  less  prominent  lines.”  Conrad,  1848. 

Length,  36  mm.;  width,  6 mm. 

Occurrence. — Xanjemoy  Formation.  West  of  Port  Tobacco,  1 mile 
southeast  of  Piseataway.  Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Family  SIPHONODENTALIIDAE. 

Genus  CADULUS  Philippi. 

Cadulus  abruptus  Meyer  and  Aldrich. 

Plate  XXIX,  Fig.  9. 

Cadulusi  ahruptus  Meyer  and  Aldrich,  1887,  Jour.  Cin.  Soc.  Nat.  Hist.,  vol.  ix.  No.  3, 
p.  40,  pi.  ii,  fig,  3. 

Cadulus  hellulus  Clark,  189.5,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Cadulus  belhdus  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  73,  pi.  xiv,  fig.  6. 

Description. — ‘‘  Rather  large,  somewhat  depressed.  Inflation  very 
near  to  the  larger  aperture  and  suddenly  decreasing.”  Meyer  and  Al- 
drich, 1886. 


160 


SYSTEMATIC  PALEONTOLOGY 


Thin,  polished,  slightly  arched;  much  contracted  near  the  anterior 
extremity;  anterior  opening  snhcircnlar,  posterior  simple. 

This  species  differs  from  C.  subcoarctatus  Gahb  in  having  the  con- 
striction begin  much  nearer  the  aperture.  There  is  no  longitudinal 
striation. 

Length,  8 mm.;  width,  1.25  mm. 

Occurrence. — Nanjemoa"  Fokmation.  Woodstock,  Head  of  Hanjemoy 
Creek,  East  and  west  of  Port  Tobacco,  H and  2J  miles  above  Popes 
Creek,  1 mile  southeast  of  Piscataway,  Upper  Marlboro  (deep  cut  near 
Chesapeake  Beach  E.  E.  station).  Well  at  Chesapeake  Beach  (90-92 
feet).  Aquia  Formation.  Aquia  Creek,  Liverpool  Point,  Clifton 
Beach,  1 mile  northeast  of  Piscataway. 

Collection. — Maryland  Geological  Survey,  Johns  Hopkins  University. 


Class  PELECYPODA. 

Order  TELEODESMACEA. 

Family  TEREDINIDAE. 

Genus  TEREDO  LinnA 
Teredo  virginiana  Clark. 

Plate  XXX,  Figs.  1,  la,  2,  2a,  3. 

Teredo  virginiana  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Teredo  virginiana  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  72,  pi.  xv,  tigs.  5a-5c. 

Teredo  virginiana  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  part  iv,  p.  813. 

Description. — “ Shell  unknown;  tube  thick,  cylindrical,  irregularly 
curved,  rapidly  tapering;  surface  smooth,  or  with  fine  lines  of  growth; 
prominent  transverse  segment  near  posterior  extremity  of  the  tube  in 
some  of  the  forms.’’  Clark,  1896. 

This  type  compared  with  the  forms  described  from  the  Alabama  Ter- 
tiary shows  various  points  of  dissimilarity,  and  even  in  the  absence  of 
the  valves  seems,  from  its  common  occurrence,  worthy  of  a name. 

The  tubes  often  occur  in  large  masses  in  pieces  of  lignite. 

Diameter  of  tube  (maximum),  5 mm. 

Occurrence. — Xanjemoi:  Formation,  J mile  below  Chapel  Point. 
Woodstock,  Hills  Bridge,  West  of  Port  Tobacco,  Upper  Marlboro  (deep 


MARYLAND  GEOLOGICAL  SURVEY 


161 


cut  near  Chesapeake  Beach  E.  E.  station).  Aquia  Formation.  Upper 
Marlboro,  2 miles  below  Potomac  Creek,  1 mile  southeast  of  Mason 
Springs,  Clifton  Beach,  1 mile  northeast  of  Piscataway. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey, 
Philadelphia  Academy  of  Natural  Sciences. 

Family  PHOLADIDAE. 

Genus  PHENACOMYA  Dali. 

Phenacomya  petrosa  (Conrad). 

Plate  XXX,  Figs.  4,  4a,  4b. 

Pholas  petrosa  Conrad,  1842,  Proc.  Nat.  Inst.,  Bull,  ii,  p.  193,  pi.  ii,  fig.  4. 

Pholas  petrosa  Conrad,  1846,  Amer.  Jour.  Sci.,  ser.  ii,  vol.  i,  p.  213,  pi.  i,  fig.  1. 

Pholas  petrosa  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  104. 

Pholas  petrosa  Conrad,  186.5,  Amer.  Jour.  Conch.,  vol.  i,  p.  2. 

Pholas  petrosa  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  9. 

Pholas  0)  petrosa  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Pholas  {‘i)  petrosa  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  73,  pi.  xv,  figs,  la-lc. 

Phenacomya  petrosa  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  part  iv,  p.  823. 

Description. — Ovate-acute;  anteriorly  profoundly  ventricose;  radii 
sharp  and  numerous;  dorsal  margin  obliquely  rectilinear  from  the  sum- 
mit of  the  umbo;  base  obliquely  subrectilinear;  posterior  side  produced, 
cuneiform.^^  Conrad,  1842. 

This  form  is  apparently  restricted  to  the  limestone  ledge,  known  as 
Zone  5. 

Length,  85  mm.;  height,  35  mm. 

Occurrence. — Aquia  Formation.  “Piscataway’’  (Conrad),  Fort 
Washington,  Aquia  Creek,  Clifton  Beach. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey, 
Philadelphia  Academy  of  Natural  Sciences. 

Family  GASTROCHAENIDAE. 

Genus  GASTROCHAENA  Spengler. 

Gastrochaena  sp. 

Plate  XXX,  Fig.  5. 

Gastrochaena  sp.  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Gastrochaena  sp.  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  73,  pi.  xv,  tig.  6. 

Casts  of  the  tubes  of  Gastrochaena  are  common  in  the  indurated  layer. 

Zone  5,  of  the  Aquia  Creek  stage,  and  also  occur  at  higher  horizons. 

11 


162 


SYSTEMATIC  PALEONTOLOGY 


Few  of  the  specimens  obtained  show  any  traces  of  the  shell  substance^ 
and  rarely  impressions  of  the  transverse  striations  of  the  tube  wall. 
Occurrence. — Aquia  Foemation.  Aqnia  Creek,  Upper  Marlboro. 
Collection. — Johns  Hopkins  University. 


Family  SAXICAVIDAE. 

Genus  PANOPEA  Menard. 

Panopea  elongata  Conrad. 

Plate  XXXI,  Figs.  1-5. 

Panopaea  elongata  Conrad,  1885,  Trans.  Geol.  Soc.  Penn.,  vol.  i,  p.  339,  pi.  xiii,  tig-.  1. 

Panopaea  elongata  Conrad,  1846,  Amer.  Jour.  Sci.,  ser.  ii,  vol.  i,  p.  215,  pi.  i,  tig:.  2.. 

Panopaea  elongata  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  103. 

Glycyrnei'is  elongata  Conrad,  1854,  Proc.  Acad.  Nat.  Sci.,  Phila.,  vol.  vii.  p.  29. 

Glycymeris  elongata  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  2. 

Glycymeris  elongata  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  8. 

Panopaea  elongata  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  4. 

Panopaea  elongata  Clark,  Bull.  141,  U.  S.  Geol.  Survey,  p.  75,  pi.  xix,  tigs,  la-lc. 

Panopea  elongata  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  pt.  iv,  p.  828. 

Description. — Shell  oblong,  produced,  surface  with  distinct  con- 
centric irregular  undulations;  beaks  distant  from  the  anterior  margin.’’ 
Conrad,  1835. 

Since  at  most  localities  casts  alone  are  found,  the  following  important 
character  has  thus  been  overlooked,  viz.,  that  the  surface  is  covered  with 
closely-set,  radiating  lines  of  minute  granules,  which  when  worn  show 
as  lines  of  punctae,  or  give  the  surface  an  irregularly  honeycombed  ap- 
jiearance. 

Length,  85  mm.;  width,  43  mm. 

Occurrence. — Aquia  Foemation.  Fort  Washington,  Winchester,. 

Piscataway  ” (Conrad),  Tinkers  Creek  1 mile  north  of  Piscataway,  1 
mile  northeast  of  Piscataway,  1 mile  southeast  of  Mason  Springs,  Har- 
desty, E.  E.  cut  near  Seat  Pleasant,  Aquia  Creek,  Potomac  Creek,  Pas- 
potansa  Creek,  2 miles  below  Potomac  Creek,  Marshall  Hall,  Upper 
]\[arll)oro,  Clifton  Beach,  Eolphs  Landing,  Glymont. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey, 
Philadelphia  Academy  of  Xatural  Sciences,  U.  S.  Xational  Museum. 


MARYLAND  GEOLOGICAL  SURVEY 


163 


Family  CORBULIDAE. 

Genus  CORBULA  Lamarck. 

CORBULA  SUBENGONATA  Dali. 

Plate  XXXII,  Figs.  1,  la,  2,  2a,  2b. 

Corhula  nasuta  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Corbula  nasuta  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  74. 

Corhula  suhengonata  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  ill,  pt.  iv,  p.  841. 

Description. — This  form  is  smaller,  less  inflated,  thinner,  and  with 
more  nearly  parallel  dorsal  and  ventral  borders  than  C.  alabamiensis. 
The  sculpture  is  finer  than  in  C.  engonata,  which  is  a more  elongated 
species.^’  Dali,  1898. 

The  species  was  thus  defined  by  Dr.  Dali  to  include  the  forms  from 
the  Chickasawan  of  Alabama,  which  had  previously  been  called  C.  ala- 
bamiensis Lea  or  C.  alabamiensis  var.  It  is  probably  the  ancestral  form 
of  the  Claibornian  C.  alabamiensis  Lea. 

This  species  is  very  common  in  the  Maryland  and  Virginia  Eocene. 
Its  slightly  elevated  umbones  and  the  absence  of  rostrated  posterior  sur- 
face separate  it  from  the  other  species  of  this  genus.  In  its  occurrence 
it  differs  from  our  other  Eocene  species  of  Corbula  in  that  it  is  most 
abundant  in  the  lower  beds. 

Length,  11  mm.;  height,  6 mm. 

Occurrence. — Xanjemoy  Formation.  Woodstock,  Popes  Creek. 
Aquia  Formation.  Glymont,  Clifton  Beach,  6 miles  east  of  Washing- 
ton, Mattawoman  Creek,  2 miles  below  Potomac  Creek,  1 mile  southeast 
of  Mason  Springs,  1 mile  northeast  of  Piscataway. 

Collectiojis. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
U.  S.  Xational  Museum. 

Corbula  aldrichi  Meyer. 

Plate  XXXII,  Figs.  3,  3a,  4,  4a,  5,  5a,  6,  6a. 

Corhula  aldrichi  Meyer,  1885,  Amer.  Jour.  Sci.,  ser.  iii,  vol.  xxx,  p.  67. 

Corhula  aldrichi  Aldrich,  1886,  Bull,  i,  Ala.  Geol,  Survey,  p.  83,  pi.  i,  fig.  21. 

Corhula  aldrichi  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Corhula  aldrichi  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  74. 

Description. — It  has  radiating  striae  on  the  umbonial  part  of  the 
surface,  a characteristic  which  I had  not  seen  before  in  a Corbula.” 
Meyer,  1885. 


164 


SYSTEMATIC  PALEONTOLOGY 


Eoimded  trigonal;  ventricose;  posterior  side  carinated;  beak  small, 
curved  anteriorly,  in  the  left  valve  nearly  in  the  middle;  right  valve 
briefly  rostrated;  in  both  valves  the  nmbonial  part  is  without  concentric 
ribs,  but  with  impressed,  radiating  lines — the  ventral  part  with  con- 
centric ribs.”  Aldrich,  1886. 

This  remarkable  form,  with  its  radiating  lines  upon  the  nmbonial 
portions  of  the  shell,  is  very  common.  The  Maryland  form  differs  in 
no  essential  particulars  from  the  Gulf  type. 

Length,  11  mm.;  height,  7 mm. 

Occurrence. — Nanjemoy  Formation.  Upper  Marlboro  (deep  cut  near 
Chesapeake  Beach  E.  E.  station).  East  and  west  of  Port  Tobacco,  Head 
of  Hanjemoy  Creek,  mile  below  Chapel  Point,  Popes  Creek,  IJ  miles 
above  Popes  Creek,  miles  above  Popes  Creek,  AVoodstock,  1 mile 
southeast  of  Piscataway.  Aquia  Formation.  Aquia  Creek,  Liverpool 
Point,  Clifton  Beach. 

Collectio7is. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
U.  S.  National  Museum. 

CoRBULA  ONiscus  Conrad. 

Plate  XXXII,  Figs.  7,  7a,  8,  8a,  8b. 

Corbula  oniscus  Conrad,  1833,  Amer.  Jour.  Sci.,  vol.  xxiii,  p,  341. 

Corbula  oniscus  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Corbula  oniscus  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  75. 

Corbula  {Aloiclis)  oniscus  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  pt.  iv, 
p.  843. 

Description. — Shell  elevated;  larger  valve  ventricose,  with  profound 
sulci  terminating  at  the  nmbonial  slope,  which  is  carinated;  posterior 
extremity  narrowed  and  truncated,  from  the  posterior  angle  of  which 
a Carina  extends  to  the  apex,  nearly  parallel  with  that  of  the  nmbonial 
slope;  superior  valve  concentrically  striated.  Length,  one-third  of  an 
inch.”  Conrad,  1833. 

This  species,  characterized  by  its  solid  form  and  numerous  concentric, 
wrinkled,  approximate  lines  and  prominently  rostrated  posterior  sur- 
face, is  common  at  several  localities  in  the  Maryland  Eocene.  None  of 
the  specimens  obtained  reach  the  size  of  the  larger  individuals  in  the 
Gulf  Eocene. 


MAKYLAXD  GEOLOGICAL  SURVEY 


165 


Length,  10  mm.;  height,  7 mm. 

Occurrence. — Nanjemoy  Formation.  East  and  west  of  Port  Tobacco, 
Woodstock,  Popes  Creek,  2^  miles  above  Popes  Creek,  Head  of  Nanjemoy 
Creek,  Upper  Marlboro  (deep  cut  near  Chesapeake  Beach  K.  E.  station), 
1 mile  southeast  of  Piscataway.  Hills  Bridge?  Aquia  Formation. 
Glymont. 

Collection. — Maryland  Geological  Survey. 

Family  SOLENIDAE. 

Genus  SOLEN  Linne. 

SoLEN  LiSBONENSis  (?)  Aldrich. 

Plate  XXXIII,  Fig.  1. 

Solen  Usbonensis  Aldrich,  1886,  Bull,  i,  Ala.  Geol.  Survey,  p.  37,  pi.  iv,  fig.  I. 

Solen  up.  Harris,  1897,  Bull.  Amer.  Pal.  No.  9,  p.  66,  pi.  xiv,  fig.  9. 

Solen  (Plectosolen)  lisbonensis  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  pt.  v, 
p.  953. 

(.^)  Solen  {Plectosolen)  lisbonensis  var.  abruptas  Dali,  1900,  Trans.  Wagner  Free  Inst. 
Sci.,  vol.  iii,  pt.  v,  p.  953. 

Description. — Shell  linear,  nearly  straight;  posterior  snbtruncate; 
anterior  obliquely  rounded  with  a depressed  space  behind  running  to  the 
beaks;  lines  of  growth  prominent,  bending  at  right  angles  along  a line 
running  obliquely  from  the  beaks  to  the  junction  of  the  posterior  and 
ventral  margins.  Anterior  widely  gaping.’^  Aldrich,  1886. 

The  references  given  above  are  the  only  records  we  have  of  the  occur- 
rence of  this  genus  in  the  Eocene  of  Eastern  Xorth  America.  The  two 
specimens  from  the  Potomac  Eiver  are  both  imperfect  and  neither  shows 
any  characters  upon  which  they  can  be  specifically  separated  from 
S.  lishonensis.  The  lines  of  growth  on  our  specimens  do  not  bend  quite 
as  sharply  as  they  do  in  AldricUs  figure.  In  this  respect  they  are  more 
like  the  figure  published  by  Professor  Harris.  Our  specimens  are 
smaller  than  either  of  those  figured  from  Alabama.  In  the  publication 
above  noted.  Dr.  Dali  describes  a variety  ahruptus  under  S.  lishonensis. 
This  differs  from  our  form  even  more  than  the  typical  S.  lishonensis 
does. 


166 


SYSTEMATIC  PALEONTOLOGY 


Length  (of  fragment),  32  mm.;  width,  9 mm. 

Occurrence. — Nanjemoy  Fokmation.  ^ mile  below  Chapel  Point, 
Woodstock. 

Collections. — Maryland  Geological  Survey,  Philadelphia  Academy  of 
Natural  Sciences  (No.  6224). 

Family  TELLINIDAE. 

Genus  TELLINA  Deshayes. 

Subgenus  ANGELUS  Megerle. 

Tellina  (Angelus)  vieginiana  Clark. 

Plate  XXXIII,  Pig.  3. 

Tellina  virginiana  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Tellina  virginiana  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  76,  pi.  xv,  flg.  4. 

Tellina  greggi  Harris,  1897,  Bull.  Amer.  Pal.  No.  9,  p.  72.  (In  part.) 

Tellina  {Angelas)  virginiana  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii, 
pt.  V,  pp.  1015,  1016. 

Description. — Shell  elongated,  thin,  compressed;  posteriorly  very 
short,  angular,  and  slightly  folded;  anteriorly  rounded  and  elongated; 
umbones  posteriorly  situated;  two  small  cardinal  teeth  and  indistinct 
lateral  teeth;  pallial  sinus  obscure.  Exterior  covered  with  fine  concen- 
tric lines  following  lines  of  growth.”  Clark,  1896. 

This  species  is  more  abundant  in  the  Nanjemoy  formation,  but  the 
specimens  from  the  Aquia  formation  are  much  larger. 

Professor  Harris  has  suggested  the  identity  of  this  form  with  T.  greggi 
of  Alabama,  but  further  study  has  shown  them  to  be  undoubtedly  dis- 
tinct. Dr.  Dali  agrees  with  us  in  this  opinion. 

Length,  38  mm.  (average,  18  mm.);  height,  25  mm.  (average,  13  mm.). 

Occurrence. — Nanjemoy  Fokmation.  Woodstock,  Popes  Creek,  East 
and  west  of  Port  Tobacco,  Charles  Branch  between  Rosary ville  and  Up- 
per Marlboro,  2J  and  3 miles  above  Popes  Creek.  Aquia  Fokmation. 
Aquia  Creek,  Clifton  Beach,  2 miles  below  Potomac  Creek,  1 mile  south- 
east of  Mason  Springs,  Fort  Washington. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University. 


MAKYLAND  GEOLOGICAL  SURVEY 


167 


Section  peronidia  dale. 

Tellina  (Peronidia  ?)  williamsi  Clark. 

Plate  XXXIII,  Figs.  2,  2a. 

Tellina  williamsi  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Tellina  williamsi  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  76,  pi.  xv,  figs.  3a,  36. 

Tellina  subtriangularis  Harris,  1897,  Bull.  Amer.  Pal.,  No.  9,  p.  73.  (In  part). 

Tellina  {Peronidia?)  williamsi  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  . 
pt.  V,  p.  1016. 

Description. — Shell  small,  rather  solid,  not  strongly  inequilateral; 
posterior  shorter;  surface  ornamented  with  elevated,  close-set  ridges  or 
lamellae,  increasing  in  size  toward  the  basal  margin;  posteriorly  suhan- 
gulated;  two  cardinal  teeth,  posterior  bifid;  lateral  teeth  strongly  devel- 
oped; pallial  sinus  deep.’^  Clark,  1896. 

The  question  of  the  identity  of  this  form  with  Tellina  subtriangularis 
Aldrich  of  the  Alabama  Eocene  has  been  carefully  considered.  Dr. 
Dali " agrees  with  us  that  they  are  distinct,  but  Professor  Harris " thinks 
they  are  the  same.  T.  williamsi  is  more  elongate  and  more  strongly 
sculptured. 

Length,  12  mm.,  height,  7 mm. 

Occurrence. — Xanjemoy  Formation.  Popes  Creek,  2^  miles  above 
Popes  Creek,  Woodstock.  Aquia  Formation.  Potomac  Creek. 

Collection. — Maryland  Geological  Survey,  Johns  Hopkins  University. 

Tellina  (Peronidia)  p^pyria  (?)  Conrad. 

{?)  Tellina  papyria  Conrad,  1833,  Fossil  Shells  of  the  Tertiary,  No.  4,  p.  41  (lig’d. 
Amer.  Jour.  Sci.,  vol.  i,  1846,  pi.  iv,  tig.  7). 

A single  specimen  has  been  found  which  belongs  to  neither  of  the  pre- 
ceding species,  and  which  has  the  outline  of  T.  papyria.  The  shell  is 
very  thin  and  has  almost  disappeared. 

Length,  35  mm.;  height,  26  mm. 

Occurrence. — Aquia  Formation.  Fort  Washington. 

Collection. — Maryland  Geological  Survey. 

* Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  pt.  v,  1900,  p.  1016. 

^Bull.  Amer.  Pal.,  No.  9,  1897,  p.  73. 


168 


SYSTEMATIC  PALEONTOLOGY 


Family  VENERIDAE. 

Genus  MERETRIX  Lamarck. 

Meretkix  lenis  (Conrad). 

Plate  XXXIII,  Fig.  4. 

Cytherea  lenis  Conrad,  1S48,  Jour,  Acad.  Nat.  Sci.  Phila.,  2nd  ser.,  vol.  i,  p.  180, 
pi.  xiv,  tig.  19. 

Description. — Longitndinally  ovate,  thin,  ventricose;  anterior  ex- 
tremity acutely  rounded;  posterior  end  direct,  snbtrnncated;  disk  with 
impressed  concentric  lines,  distinct  on  the  sides  hut  obsolete  in  the 
middle  of  the  valves;  lunnle  long,  cordate,  defined  by  an  impressed  line; 
inner  margin  entire.^^  Conrad,  1848. 

This  species  is  distinguished  from  its  associates  by  its  extremely  ele- 
vated beaks,  and  deep  valves.  The  shell  is  very  thin  and  fragile  and 
tends  to  break  along  radiating  lines.  The  concentric  wrinkles  and  lines 
of  growth  are  very  distinct  toward  the  beak,  hut  become  less  so  toward 
the  periphery. 

Length,  11  mm.;  height,  11  mm. 

Occurrence. — Xanjemoy  Formation.  Woodstock,  Kavine  north  of 
Thrift  (?). 

Collections. — Maryland  Geological  Survey,  Philadelphia  Academy  of 
Natural  Sciences  (No.  6384). 

Meretrix  ovata  yar.  ovata  (Rogers). 

Plate  XXXIV,  Figs.  1,  la. 

Cytherea  ovata  Rogers,  1837,  Trans.  Amer.  Philos.  Soc.,  vol.  v,  p.  340;  vol.  vi, 
pi.  xxvii,  fig.  2.  (Reprint  Geol.  of  the  V'irginias,  1884,  p.  668,  pi.  ii,  fig.  2.) 

Cytherea  liciata  Conrad,  1848,  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  ser.,  vol.  i,  p.  131, 
pi.  xiv,  fig.  20. 

Cytherea  ovata  H.  C.  Lea.,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  99. 

Cytherea  liciata  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  99. 

Meretrix  liciata  Conrad,  1854,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  vii,  p.  30. 

Meretrix  ovata  Conrad,  1854,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  vii,  p.  30. 

Diove  ovata  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  6. 

Bione  liciata  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  6. 

Dione  ovata  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  7. 

Bione  liciata  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  7. 

Cytherea  ovata  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5.  (In  part.) 

Cytherea  ovata  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  76.  (In  part.l 


MAEYLAXD  GEOLOGICAL  SURVEY 


169 


Description. — Shell  suhovate,  somewhat  inflated,  with  concentric 
transverse  striae,  very  fine  near  the  nmhones,  hnt  much  coarser  near  the 
margin;  beaks  rather  elevated;  Innnle  very  indistinct;  teeth  elevated  and 
straight,  the  two  posterior  ones  of  the  left  valve  small,  much  compressed, 
approximate,  and  nearly  parallel;  the  anterior  tooth  large  and  grooved 
by  a deep  canal;  cavity  of  shell  deep;  margin  entire;  posterior  margin 
straight,  and  separated  from  the  muscular  impression  by  a fold  or  groove. 
Length  one  and  one-tenth  of  an  inch;  height  eighty-five  hundredths  of 
an  inch.^’  Eogers,  1837. 

This  widely-distributed  species  shows  great  variation  in  outline  and 
has  been  described  under  several  names,  of  which  only  the  Maryland 
names  are  given  in  the  synonymy.  The  complete  species  includes  M. 
nuttalliopsis  Heilprin  with  all  its  varieties,  and  a number  of  other  Ala- 
bama names. 

The  species  ranges  from  the  base  to  the  summit  of  the  Maryland 
Eocene,  and  is  very  abundant  in  nearly  all  localities.  The  two  varieties 
may  be  clearly  recognized  and  their  separation  closely  confot-ms  to  the 
stratigraphic  divisions. 

The  form  originally  described  by  Eogers  comes  from  the  Xanjemoy 
formation.  It  is  smaller,  thinner,  in  general  more  elongate,  and  with 
a less  rounded  basal  margin  than  the  older  type.  It  was  this  variety 
that  Conrad  afterward  named  liciata. 

Length,  31  mm.;  width,  24  mm. 

Occurrence. — Xaxjemoy  FoR^iiATiox.  East  and  west  of  Port  To- 
bacco, Popes  Creek,  1 to  2^  miles  above  Popes  Creek,  ^ mile  below 
Chapel  Point,  Upper  Marlboro  (deep  cut  near  ^Chesapeake  Beach  E.  E. 
station).  Upper  Marlboro  (southwest  of  town  near  forks  of  roads).  Head 
of  Xanjemoy  Creek,  1 mile  southeast  of  Piscataway. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
Philadelphia  Academy  of  Xatural  Sciences,  U.  S.  Xational  Museum. 

Meretrix  ovata  VAR.  PYGA  Conrad. 

Plate  XXXIV,  Figs.  2,  2a,  3,  3a,  4,  5. 

Cythei'ea  pyga  Convady  184S,  Jour.  Acad.  Nat.  Sci.  Pliila.,  2nd  ser.,  vol.  i,  p.  131, 
pi.  xiv,  flff.  18. 

Cytherea  pyga  II.  C.  Lea,  1848,  Proc.  Acad.  Xat.  Sci.  Phila.,  vol.  iv,  p.  09. 


170 


SYSTEMATIC  PALEONTOLOGY 


Meretrix  pyga  Conrad,  1854,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  vii,  p.  30. 

Dione  pyga  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  6. 

Cytherea  ovata  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5.  (In  part.) 

Cytherea  ovata  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  76  (In  part),  pi.  xvi, 
figs.  la-1/. 

Description. — Siiboval,  ventricose,  thick,  with  closely  arranged  ro- 
bust concentric  lines;  nnibo  wide,  prominent  above;  dorsal  margin  very 
oblique,  rounded;  posterior  extremity  obtusely  and  obliquely  rounded 
inwards;  anterior  extremity  much  narrower  than  the  posterior,  and 
more  acutely  rounded;  liinnle  lanceolate,  defined  by  a distinct  impressed 
line;  cardinal  teeth  robust.  Length,  If;  height.  If/’  Conrad,  1848. 

The  form  described  by  Conrad  under  this  name  was  found  in  the 
Aqnia  formation,  and  the  name  as  here  used  is  thus  restricted.  The 
specimens  are  large,  thick,  ventricose,  and  more  nearly  oval  than  the 
variety  from  the  Nanjemoy  formation. 

Length,  50  mm.;  width,  43  mm. 

Occurrence. — Aqijia  Foiimation.  Potomac  Creek,  Aqnia  Creek,  Fort 
Washington,  Glymont,  Month  of  Paspotansa  Creek,  Liverpool  Point, 
Sheckel’s  Farm  near  South  Eiver,  Clifton  Beach,  2 miles  below  Potomac 
Creek,  1 mile  northeast  of  Grimesville,  Upper  Marlboro,  Hardesty, 
Brooks  Estate  near  Seat  Pleasant,  2 miles  west  of  Collington,  Eeedy  Eiin 
(branch  of  Chickomnxen  Creek),  Mattawoman  Creek  (?),  1 mile  south- 
east of  Mason  Springs. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
Philadelphia  Academy  of  Natural  Sciences,  U.  S.  National  Museum. 

Meretkix  subimpressa  Conrad. 

Plate  XXXIII,  Figs.  5,  5a,  6,  7,  8,  8a,  9,  9a. 

Cytherea  subimpressa  Conrad,  1848,  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  ser.,  vol.  i, 
p.  130,  pi.  xiv,  fig.  26. 

Cytherea  subimpressa  II.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  99. 

Meretrix  subimpressa  Conrad,  1854,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  vii,  p.  30. 

Cytherea  subimpressa  CHv'k,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Cytherea  subimpressa  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  77,  pi.  xvii,  figs. 
la-17i. 

Description. — Ovate,  slightly  ventricose,  smooth  and  polished,  with 
concentric,  slightly  impressed  lines  on  the  anterior  side;  anterior  side 


MAKTLAXD  GEOLOGICAL  SUETEY 


m 


short,  rather  acutely  rounded;  posterior  side  produced,  acutely  rounded 
at  the  extremity;  dorsal  margin  long,  oblique,  slightly  curved;  beaks 
prominent;  lunule  lanceolate;  defined  by  a slightly  impressed  line. 
Length,  inch;  height,  8-10  inch.’’  Conrad,  1848. 

This  species  is  very  abundant  in  the  AVoodstock  member  of  the  Xan- 
jemoy  formation. 

Length,  30  mm.;  width,  18  mm. 

Occurrence. — Xaxjemoi:  FoKiiATiox.  Popes  Creek,  1 mile  southeast 
of  Piscataway,  AA'oodstock,  Upper  Marlboro  (southwest  of  town  near 
forks  of  two  roads). 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
Philadelphia  Academy  of  Xatural  Sciences. 


Genus  DOSINIOPSIS  Conrad 
Dosixiopsis  LEXTicuLAKis  (Eogers). 

Plate  XXXA^,  Figs,  la-lg. 

Cytherea  lenticularis'Rogevs,  1839,  Trans.  Amer.  Philos.  Soc.,  toI.  vi,  p.  372,  pl.xxviii, 
tig.  1. 

Cytherea  lenticularis  H.  C.  Lea,  1848,  Proc.  Acad.  Xat.  Sci.  Phila.,  vol.  iv,  p.  99. 
Artemis  lenticularis  Conrad,  1853,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  vi,  p.  320. 
Bosinia  lenticularis  Conrad,  1854,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  vii,  p.  30. 
Dosiniopsis  meekii  Conrad,  1864,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  xvi,  p.  213,  and 
tigure  in  text. 

Dosiniopsis  lenticularis  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  6. 

Dosiniopsis  rneekii  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  6. 

Dosiniopsis  rneekii  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  6. 

Dosmiopsis  lenticularis  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  6. 

Dosiniopsis  lenticularis  Harris,  1894,  Amer.  Jour.  Sci.,  ser.  iii,  vol.  xlvii,  p.  302. 
Dosiniopsis  lenticularis  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 
Dosiniopsis  lenticularis  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  78,  pi.  xviii, 
tigs,  la-l^r. 

Description. — Shell  large,  depressed,  discoidal,  rather  thick,  length 
nearly  equal  to  the  breadth;  transversely  striated;  lunule  long,  ovate, 
obscurely  defined  by  a very  faint  impressed  line;  umbones  rather  de- 
pressed; beaks  small,  hardly  recurved;  teeth  straight,  divergent;  cavity 
of  the  shell  not  deep;  margin  entire.  Diameter  about  two  inches.” 
Eogers,  1839. 

The  type  of  the  species,  as  figured  and  described  by  Eogers,  is  a much 


172 


SYSTEMATIC  PALEONTOLOGY 


less  common  form  than  the  variety  later  described  by  Conrad  under  the 
name  of  B.  meekii.  Eogers’s  type  represents  a moderately  thin  shell  with 
a weak  hinge,  while  the  form  described  by  Conrad  is  a heavy  shell  with 
a broad,  solid  hinge.  Every  possible  gradation  between  these  extremes 
has  been  obtained. 

Length,  70  mm.;  height,  70  mm. 

Occurrence. — Aquia  Eoemation.  Fort  Washington,  Glymont,  Clif- 
ton Beach,  Potomac  Creek,  Liverpool  Point,  Aqnia  Creek,  Mattawoman 
Creek,  1 mile  northeast  of  Piscataway,  Sheckels  Farm  near  South  Eiver, 
Eeedy  Eun  (branch  of  Chickomnxen  Creek),  1 mile  west  of  Hardesty, 
near  Hardesty,  Brooks  Estate  near  Seat  Pleasant,  1 mile  northeast  of 
Grimesville,  Harrisons  Landing,  Upper  Marlboro,  3 miles  west  of  Pisgah, 
Fredericktown. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
U.  S.  National  Museum,  Philadelphia  Academy  of  Natural  Sciences. 

Family  CARDIIDAE. 

Genus  PROTOCARDIA  Beyrich. 

Protocardia  lenis  Conrad. 

Plate  XXXVI,  Figs.  1,  la,  2,  2a,  3. 

Cardinm  {Protocardia)  lenis  Conrad,  1855,  Proc.  Acad.  Nat.  Sci.  Pliila.,  vol.  vii, 
p.  258. 

Protocardia  virginiana  Conrad,  1864,  Proc.  Acad.  Nat.  Sci.  Pbila.,  vol.  xv,  p.  211. 

Protocardia  virginiana  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  6. 

Protocardia  virginiana  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Protocardia  virginiana  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  81,  pi.  xxvi, 
tigs,  la-lc. 

Protocardia  lenis  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  pt.  v,  p.  1113. 

Description. — Compared  with  C.  nicolletti;  nmho  less  inflated,  pos- 
terior margin  oblique,  shell  proportionally  longer,  and  the  radiating 
lines  22;  in  the  other  25.  The  posterior  cardinal  tooth  larger,  &c.^^ 
Conrad,  1855. 

Cordate,  snhtriangnlar,  inequilateral,  ventricose,  thin;  radiating  lines 
minute;  anterior  upper  margin  very  oblique,  slightly  emarginate,  pos- 
terior side  slightly  produced,  the  margin  obliquely  truncated;  post-nm- 
honal  area  densely  tnhercnlated  on  closely  arranged  striae;  posterior  car- 


MARYLAND  GEOLOGICAL  SURVEY 


173 


dinal  tooth  small,  tubercular.  Height,  1-|  inch;  length.  If  inch." 
Conrad,  1864. 

This  species  has  a wide  vertical  and  horizontal  range  in  the  Maryland 
Eocene.  It  is  hy  no  means  a common  form,  and  good  specimens  are 
very  rare. 

Certain  Gulf-state  forms  have  been  referred  to  this  species,  hut  the 
recent  work  of  Dr.  Dali  shows  that  they  are  distinct  and  that  this  species 
is  apparently  restricted  to  Maryland  and  Virginia. 

Length,  42  mm.;  width,  42  mm. 

Occurrence. — Hanjemoy  Formation.  Popes  Creek,  Woodstock. 
Aquia  Formation.  Aquia  Creek,  Potomac  Creek,  1 mile  southeast  of 
Mason  Springs,  2 miles  below  Potomac  Creek,  Upper  Marlboro,  Eolphs 
Landing,  1 mile  northeast  of  Piscatawa}^  mouth  of  Paspotansa  Creek. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
Philadelphia  Academy  of  Natural  Sciences. 

Family  DIPLODONTIDAE. 

Genus  DIPLODONTA  Broun. 

Diplodonta  marlboroensis  n.  sp. 

Plate  XXXVI,  Fig.  4. 

Description. — Shell  subcircular,  moderately  and  regularly  convex. 
Beaks  depressed,  approximate.  Lines  of  growth  weak.  Surface  irregu- 
larly wrinkled,  sometimes  smooth  and  almost  polished. 

Differs  from  D.  liopTcinsensis  Clark  in  being  larger,  more  elevated, 
much  less  globose,  having  a less  prominent  beak,  and  much  weaker  and 
less  frequent  lines  of  growth. 

This  species  has  a resemblance  to  D.  ungulifera  Conrad.  The  resem- 
blance is  especially  close  with  Lea’s  figure  of  that  species  (described  as 
Egeria  rotunda). 

Length,  18  mm.;  width,  16  mm.;  depth  of  valve,  4 mm. 

Occurrence. — Aquia  Formation.  Upper  Marlboro,  SlieckeFs  Farm 
near  South  Eiver. 

Collection. — Maryland  Geological  Survey. 


174 


SYSTEMATIC  PALEONTOLOGY 


Diplodonta  hopkinsensis  Clark. 

Plate  XXXVI,  Figs.  5,  5a,  6,  7. 

Biploclonta  hopkinsensis  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Diplodonta  hopkinsensis  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  79,  pi.  xxii, 
figs.  la-lfZ. 

Diplodonta  hopkitisensis  Dali,  1900,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  pt.  v, 

p.  1181. 

Description. — “ Shell  small,  suhorbicular,  globose;  surface  with  fine  in- 
distinct striations;  anteriorly  and  posteriorly  rounded.’’  Clark,  1896. 

This  species  has  not  been  found  in  Maryland,  hut  as  it  occurs  in  the 
same  beds  in  Virginia  it  will  undoubtedly  he  found  in  Maryland  later, 
and  for  this  reason  the  figures  and  description  are  reprinted  for  the 
benefit  of  future  investigators. 

Dr.  Dali  records  several  localities  in  the  Chickasawan  of  Alabama. 

Length,  16  mm.;  height,  15  mm. 

Occurrence. — Xanjemoy  Formation.  Evergreen,  Va. 

Collection. — Johns  Hopkins  University. 

Family  LUCINIDAE. 

Genus  LUCINA  Bruguih'e. 

Lucina  aquiana  Clark. 

Plate  XXXVII,  Figs.  1,  la. 

Lucina  aquiana  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Lucina  aquiana  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  78,  pi.  xx,  figs,  la,  16. 

{?)  Lucina  greggi  Harris,  1897,  Bull.  Amer.  Pal.  No.  9,  p.  70  (In  part),  pi.  xiv,  fig. 
2a  (not  fig.  2). 

Description. — “ Shell  of  moderate  size,  somewhat  compressed;  surface 
covered  with  numerous  concentric  striae;  umhones  depressed  and  acumi- 
nate on  account  of  prominent,  deeply  incised  lunules;  anterior  side  elon- 
gate; posterior  side  rounded;  hinge  with  two  cardinal  and  two  lateral 
teeth.”  Clark,  1896. 

The  smaller  figure  published  by  Professor  Harris  of  a specimen  from 
Gregg’s  Landing,  Ala.,  is  indistinguishable  from  this  species. 

Length,  18  mm.;  height,  18  mm. 

Occurrence. — Aquia  Formation.  Aquia  Creek,  Upper  Marlboro. 

Collections. — U.  S.  Xational  Museum,  Maryland  Geological  Survey. 


MARYLAND  GEOLOGICAL  SURVEY 


175 


Lucina  astartiformis  Aldrich. 

Plate  XXXA^II,  Figs.  2,  2a. 

Lxicina  astartiformis  Aldrich,  1897,  Bull.  Amer.  Pal.  No.  8,  p.  15,  pi.  v,  figs.  1,  la. 

Description. — “Shell  small^  rather  solid;  beak  pointed  and  small;  sur- 
face with  numerous  concentric  raised  lamellae  which  nearly  overlap  at 
ventral  margin;  between  the  striae  are  fine  radiating  lines  from  beak  to 
margin;  striae  terminating  at  hinge  line  in  raised  points;  hinge  long 
and  narrow;  anterior  of  shell  concave  along  the  hinge  line;  escutcheon 
smooth;  cardinal  teeth  separated  by  a deep  quadrangular  fosset;  no  lat- 
erals; muscular  impressions  distinct;  pallial  line  simple;  posterior  part  of 
valves  somewhat  flattened;  margin  smooth.’^  Aldrich,  1897. 

The  number  of  raised  lamellae  and  the  distance  between  them  are 
very  variable  factors.  This  species  is  very  rare. 

Length,  6 mm.;  width,  5.5  mm. 

Occurrence. — XxVNJemoy  Formation.  1 mile  southeast  of  Piscata- 
way.  Tapper  Marlboro  (deep  cut  near  Chesapeake  Beach  R.  R.  station). 

Collection. — Maryland  Geological  Survey. 

Lucina  dartoni  Clark. 

Plate  XXXA^II,  Figs.  3,  3a,  3h. 

Lucina  dartoni  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Lucina  dartoni  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  79,  pi.  xx,  figs.  2a~2c. 

Description. — “ Shell  rather  small,  suhorhicular,  thin;  surface  with 
fine,  thin,  distant  concentric,  lamellated  striae,  crossed  by  numerous 
radial,  fine,  irregular  lines  less  distant  than  the  concentric  lamellae;  an- 
teriorly and  posteriorly  high  shouldered  and  angulated;  lunules  large; 
hinge  area  narrow;  ligament  small;  muscle  impressions  shallow;  margin 
simple.^’  Clark,  1896. 

Length,  9 mm.;  width,  7.5  mm. 

Occurrence. — Xanjemoy  Formation.  Popes  Creek,  24  miles  above 
Popes  Creek,  Woodstock. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 


176 


SYSTEMATIC  PALEONTOLOGY 


Lucina  uhleki  Clark. 

Plate  XXXVII^  Figs.  4,  5,  6,  7. 

Lucina  ulileri  Clark,  1895,  Johns  Hopkins  Unii".  Circ.,  yol.  xv,  p.  5. 

Lucina  uhleri  Clark,  189(5,  Bull.  141,  U.  S.  Geol.  Survey,  p.  79,  pi.  xxi,  figs.  la-\d. 

{?)  Lucina  ulrichi  Harris,  1897,  Bull.  Amer.  Pal.  No.  9,  p.  71,  pi.  xiv,  fig.  4. 

Description. — Shell  small,  orbicular,  slightly  tumid;  surface  with  nu- 
merous uniform,  elevated,  concentric  ridges;  anterior  and  posterior  sides 
rounded;  lunules  slightly  depressed;  interior  with  radiating  striae;  mar- 
gin simple.^^  Clark,  1896. 

The  original  figures  of  this  species  did  not  show  the  muscular  scars 
and  the  teeth  accurately.  The  figures  here  published  correct  these  de- 
fects. 

It  is  evident  that  Professor  Harris  has  spelled  the  name  ulrichi  unin- 
tentionally. The  form  from  Wood’s  Bluff  is  probably  the  same  as  that 
from  Maryland.  The  apparent  difference  in  the  hinge,  noted  by  Pro- 
fessor Harris  being  an  inaccuracy  in  the  old  figures  which  are  here  re- 
placed by  a correct  one.  It  would  he  a misfortune  if  we  had  to  use  two 
names,  as  nearly  alike  as  uhleri  and  ulrichi,  for  two  forms  with  as  slight 
differences  as  these  show. 

This  is  the  most  abundant  and  widely  distributed  of  our  Maryland 
Eocene  Lucinas. 

The  types  are  immature. 

Length,  9 mm.;  height,  8 mm. 

Occurrence. — Xanjemoy  Fokmation.  Popes  Creek,  Woodstock. 
Aquia  Fokmation.  Clifton  Beach,  LTpper  Marlboro,  Potomac  Creek, 
Glymont,  1 mile  northeast  of  Piscataway,  Mattawoman  Creek,  1 mile 
southeast  of  Mason  Springs,  2 miles  below  Potomac  Creek,  Liverpool 
Point. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University. 

Lucina  whitei  Clark. 

Plate  XXXVII,  Figs.  8,  8a,  9. 

Lucina  whitei  Clark,  1895,  Johns  Hopkins  Unix.  Circ.,  vol.  xv,  p.  5. 

Lucina  whitei  Clark,  189G,  Bull.  141,  U.  S.  Geol.  Survey,  p.  79,  pi.  xx,  ligs.  3«-3c. 

Description. — Shell  small,  suhorhicular,  globose;  surface  with  promi- 
nent concentric  lamellae,  interrupted  posteriorly  by  shallow  fold,  extend- 


MARYLAND  GEOLOGICAL  SURVEY 


177 


ing  from  iimbones  to  posterior  basal  margin;  Innules  deeply  depressed; 
anterior  side  high  shouldered,  rounded;  posterior  high  shouldered,  angu- 
lated;  margin  crenulated/’  Clark,  1896. 

Length,  8 mm.;  width,  7.5  mm. 

0ccurre7ice. — Nanjemoy  Formation.  IVest  of  Port  Tobacco,  ^ mile 
below  Chapel  Point,  Woodstock. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

Lucina  sp. 

A single  fragment,  evidently  of  a large  Lucina,  was  found,  which  is 
very  different  from  any  other  form  known  from  Maryland  or  Virginia. 
It  probably  belongs  to  a new  species  of  Lucina,  or  to  L.  claibornensis 
Con.;  but  our  only  specimen  is  too  imperfect  to  determine.  The  shell  is 
fragile,  moderately  thin,  and  the  valves  very  shallow.  It  has  about 
forty,  rugose,  concentric  lamellae  with  faint,  wavy,  radiating  lines  be- 
tween them.  Hinge,  scars,  and  pallial  line  are  unknown.  Length  and 
height  about  30  mm. 

Occurrence. — Hanjemoy  Formation.  Popes  Creek. 

Collection. — Maryland  Geological  Survey. 

Family  CARDITIDAE. 

Genus  VENERICARDIA  Lamarck. 

This  genus  is  very  abundantly  represented  in  the  Maryland  Tertiary 
and  especially  in  the  Eocene.  The  Eocene  forms  are  very  numerous  and 
range  throughout  the  entire  horizontal  and  vertical  extent  of  the  forma- 
tions. The  variation  in  form  is  very  great  and  has  led  to  the  establish- 
ment of  several  species  and  varieties,  all  of  which  have  been  referred 
by  most  later  authors  to  F.  plaiiicosta.  Three  forms,  possessing  con- 
stant differences,  ma}^  be  recognized,  and  as  these  are  each  definitely 
restricted  in  stratigraphic  range,  and  are  hence  of  geologic  value,  they 
are  given  names. 

Rogers^  described  from  Virginia  a species  of  Yejiericardia  which  he 
called  F.  ascia.  As  this  form  has  never  been  recognized  from  Mary- 

1 Trans.  Amer.  Philos.  Soc.,  vol.  vi,  1839,  p.  374,  pi.  29,  fig.  2. 

12 


178 


SYSTEMATIC  PALEONTOLOGY 


land,  no  reference  is  made  to  it  in  the  synonymy.  If  the  figure  and 
description  are  correct,  it  is  probably  a different  species  from  any  in 
Maryland. 

Venekicaedia  planicosta  vak.  kegia  Conrad. 

Plate  XXXVIII,  Figs.  1,  la;  Plate  XXXIX,  Figs.  1,  la; 

Plate  XL,  Figs.  1,  2,  3. 

Cardita  planico&ta  Conrad,  1832,  Fossil  Shells  of  the  Tertiary,  No.  1,  [1st.  edit.] 
p.  20,  pi.  V,  fig.  2. 

Cardita  planicosta  Morton,  1834,  Syn.  Org.  Rem.  Cretaceous  Group,  App.,  p.  7. 

Venericardia  planicosta  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  107. 

Venericardia  planicosta  var.  regia  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  8. 

Venericardia  planicosta  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  5. 

Venericardia  regia  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  5. 

Cardita  planicosta  Heilprin,  1884,  Contrih.  Tert.  Geol.  and  Pal.,  p.  87. 

Venericardia  planicosta  var.  regia  Harris,  Amer.  Jour.  Sci.,  ser.  iii,  vol.  xlvii, 
p.  302. 

Venericardia  planicosta  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Venericardia  planicosta  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  80,  pi.  xxi, 
fig.  3 ; pi.  xxii,  fig.  2 ; pi.  xxiii,  figs,  la  (?)  15  (?)  Ic;  pi.  xxiv,  figs,  la  (?)  15  (?) 
Ic;  pi.  XXV,  figs,  la-lc. 

Description. — The  form  originally  described  and  figured  by  Conrad, 
which  he  subsequently  called  V.  regia,  seems  to  correspond  very  closely 
to  the  original  V.  planicosta  of  Europe.  Conrad  describes  it  as  follows: 
Cordate;  ribs  about  22,  broad  and  flattened,  separated  by  a narrow 
groove  which  becomes  obsolete  at  the  base;  ribs  near  the  posterior  end 
narrow,  indistinct,  and  crossed  by  numerous  strong  wrinkles;  lunule 
small;  cordate,  profoundly  impressed;  inner  margin  crenate.’’  Conrad, 
1832. 

This  form  is  the  largest  of  our  Eocene  Venericardias  and  is  widely 
distributed  in  and  restricted  to  the  Aquia  formation.  It  is  readily  dis- 
tinguished by  its  size,  and  its  broad,  flat  ribs,  which  do  not  become  obso- 
lete. 

Length,  110  mm.;  width,  100  mm. 

Occurrence.— Aqm A Formation.  Upper  Marlboro,  1 mile  west  of 
Hardesty,  Sheckels  Farm  near  South  Eiver,  1 mile  northeast  of  Piscat- 
away,  Xear  Annapolis,  Aquia  Creek,  Potomac  Creek,  Collington, 
Rolphs  Landing,  Mouth  of  Paspotansa  Creek,  Fredericktown  (Cecil 


MAKYLAND  GEOLOGICAL  SURVEY 


179 


Comity),  Fort  IVashington,  South  Eiver  at  mouth  of  Broad  Creek,  Severn 
Eiver,  Piscataway  (Conrad’s  original  locality),  2 miles  below  Potomac 
Creek. 

Collections. — Maryland  Geological  Survey,  Philadelphia  Academy  of 
Aatural  Sciences,  Johns  Hopkins  University,  U.  S.  National  Museum. 

Yenericardia  marylandica  n.  sp. 

Plate  XL,  Figs.  7,  7a. 

Description. — Shell  thin;  outline  circular;  valves  shallow;  about  37 
ribs,  broad  and  flat  on  top,  with  deep,  narrow  interspaces  near  the  beaks, 
but  very  flat,  and  separated  by  narrow,  impressed  line  toward  the  peri- 
phery. 

This  species  resembles  very  closely  in  outline  F.  pectuncularis  from 
the  Paris  Basin.  It  is  restricted  to  the  Woodstock  substage. 

Length,  80  mm.;  width,  80  mm. 

Occurrence. — Xanjemoy  Formation.  2 and  2^  miles  above  Popes 
Creek,  Popes  Creek,  Woodstock. 

Collection. — Maryland  Geological  Survey. 

Yenericardia  potapacoensis  n.  sp. 

Plate  XL,  Figs.  4,  5,  oa,  6,  6a. 

Description. — Shell  small,  very  thick;  valves  relatively  deep,  and  elon- 
gate along  the  line  of  the  beak  and  posterior  basal  margin;  beak  an- 
teriorly situated;  lines  of  growth  strong;  ribs  20  to  24  in  number,  ele- 
vated and  crenulated  toward  the  beak,  and  obsolete  toward  the 
periphery;  lunule  deeply  impressed;  muscular  scars  deeply  impressed; 
margin  strongly  crenulate. 

This  form  is  restricted  to  the  Xanjemoy  formation,  and  is  most 
typically  developed  in  the  lower  or  Potapaco  substage.  Figure  4 repre- 
sents the  typical  Potapaco  form.  Figures  5 and  6 show  the  Woodstock 
form. 

Length,  40  mm.;  width,  33  mm. 

Occurrence. — Xanjemoy  Formation.  East  and  west  of  Port  Tobacco, 
Popes  Creek,  Woodstock,  -J  mile  below  Chapel  Point,  Head  of  Xanjemoy 


180 


SYSTEMATIC  PALEONTOLOGY 


Creek,  Potomac  Creek  (50  feet  from  top  of  bluff),  1 mile  southeast  of 
Piseataway,  La  Plata,  Upper  Marlboro  (gully  southwest  of  town),  2 and 
2J  miles  above  Popes  Creek. 

Collections. — Maryland  Geological  Survey,  U.  S.  National  Museum, 
Philadelphia  Academy  of  Natural  Sciences. 

Family  CRASSATELLITIDAE. 

Genus  CRASSATELLITES  Kruger. 

Ceassatellites  alaefoemis  (Conrad). 

Plate  .XLI,  Figs.  1-8. 

Crassatella  alaeformis  Conrad,  1830,  Jour.  Acad.  Nat.  Sci.  Phila.,  vol.  vi,  p.  228, 
pi.  X,  fig.  1. 

Crassatella  alaeformis  Morton,  1834,  Syn.  Org.  Rem.  Cretaceous  Group,  App.,  p.  7. 
Crassatella  capri-cranium.  Rogers,  1839,  Trans.  Am.  Phil.  Soc.,  new  series,  vol.  vi, 
p.  375,  pi.  XXX,  fig.  2.  (Reprint:  Geology  of  the  Virginias,  1884,  p.  672, 
pi.  V,  fig.  2.) 

Crassatella  alaeformis  Conrad,  1846,  Amer.  Jour.  Sci.,  ser.  ii,  vol.  i,  p.  396, 
pi.  iii,  fig.  3. 

(?)  Crassatella  pahnula  Conrad,  1846,  Amer.  Jour.  Sci.,  ser.  ii,  vol.  i,  p.  396,  pi.  iv, 
fig.  1. 

Crassatella  alaeformis  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  98. 
Crassatella  capri-cranium  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  98. 
Crassatella  alaeformis  d’Orbigny,  1850,  Prodrome,  vol.  ii,  p.  383. 

Crassatella  capri-cranium  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  10. 

Crassatella  alaeformis  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  10. 

Crassatella  alaeformis  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  5. 

Crassatella  capri-cranium  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  5. 

Crassatella  declivis  Heilprin,  1880,  Proc.  U.  S.  Nat.  Museum,  vol.  iii,  pp.  151,  152, 
pi.  facing  p.  150,  fig.  9. 

Crassatella  protexta  de  Gregorio,  1890,  Ann.  Geol.  et  Pal.,  pi.  xxv,  fig.  12. 

Crassatella  alaeformis  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 
Crassatella  alaeformis  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  81,  pi.  xxvii, 
figs,  ia-lk. 

(?)  Crassatella  pal mula  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  93. 

Crassatella  declivis  Aldrich,  1897,  Bull.  Amer.  Pal.  No.  8,  p.  4,  pi.  iii,  figs.  1,  la. 

Description. — Shell  transversely  ovate  oblong;  anterior  side  ros- 
trated; posterior  side  short  and  rounded;  umbones  transversely  sulcated; 
margin  slightly  crenulated  within.’’  Conrad,  1830. 

The  variations  in  C.  alaeformis  Conrad  are  so  great  that  in  the  ab- 
sence of  connecting  forms  one  would  be  led  to  consider  the  existence  of 
several  well-defined  species.  After  a careful  study  of  a large  amount  of 


MARYLAND  GEOLOGICAL  SURVEY 


181 


material  belonging  to  this  important  species,  it  appears  that  the  forms 
figured  and  described  by  Eogers  and  Heilprin  as  distinct  species  are  only 
varieties  of  Conrad’s  C.  alaefoiinis.  The  species  is  largely  represented 
in  the  lower  portion  of  the  Middle  Atlantic  Coast  series,  especially  in 
the  Piscataway  snbstage  of  the  Aqnia  formation.  It  is  rarer  in  the  Pas- 
potansa  snbstage,  and  here  two  distinct  forms  are  found,  each  different 
from  the  older  forms.  The  specimens  from  the  sandy  beds  along  the 
Potomac  are  small  and  very  elongate,  the  average  size  being  40  x 20  mm. 
The  indurated  ledge  at  Upper  Marlboro,  Hardesty,  South  Eiver  bridge, 
and  Eolphs  Landing  contains  a very  large  form  at  the  other  end  of  the 
alaeformis  series.  This  reaches  the  size  and  proportions  of  90  x 60  mm., 
but  a single  specimen  from  South  Eiver,  which  may  however  belong  to 
another  species,  attains  the  size  of  95  x 80  mm.  The  larger  elongate 
forms  approach  the  several  Miocene  species  in  size  and  outline.  The 
specimens  from  the  various  beds  of  the  Piscataway  substage  vary  greatly 
in  size  and  form  and  connect  the  Paspotansa  varieties  with  each  other 
and  almost  connect  them  with  C.  aquiana.  C.  palmula  Conrad  prob- 
ably belongs  in  this  series. 

Length,  40  to  90  mm.;  height,  20  to  60  mm. 

Occurrence. — Aquia  Formation.  Paspotansa  Creek,  2 miles  below 
Potomac  Creek,  Potomac  Creek,  1 mile  southeast  of  Mason  Springs,  Clif 
ton  Beach,  Clymont,  Mattawoman  Creek,  Liverpool  Point,  Wades  Bay, 
Aquia  Creek,  1 mile  northeast  of  Piscataway,  Brooks  Estate  near  Seat 
Pleasant,  Fort  Washington,  Upper  Marlboro,  3 miles  west  of  Leeland  on 
Western  Branch,  West  of  Collington,  between  Buena  Vista  and  Colling- 
ton,  SheckeFs  Farm  near  South  Eiver,  Eolphs  Landing. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
U.  S.  National  Museum,  Philadelphia  Academy  of  Natural  Sciences. 

Crassatellites  aquiana  (Clark). 

Plate  XIJI,  Figs.  1,  2a,  2b. 

CrciHmtella  aquiana  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Crassatella  aquiana  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  82,  pi.  xxvi,  figs. 

2a-Zc. 

Description. — Shell  moderately  large,  attenuated  posteriorly;  surface 
w4th  a few  broad,  shallow,  concentric  furro\vs,  indicating  periods  of 


182 


SYSTEMATIC  PALEONTOLOGY 


growth,  and  fine  concentric  lines,  often  obscure;  Innules  broad,  deeply 
depressed. 

This  species  differs  from  C.  alaeformis  by  its  shorter,  broader  pos- 
terior extremity;  by  the  absence  of  deep,  prominent  furrows  on  the  nm- 
bones,  and  by  the  nmbones  themselves  being  higher.’^  Clark,  1896. 

This  species  shows  considerable  variation  in  size  and  form,  sometimes 
approaching  the  more  elevate  varieties  of  C.  alaeformis.  On  the  other 
hand  it  frequently  becomes  so  short  and  elevate  as  to  approach  Astarte 
in  outline.  This  species  is  most  abundant  in  the  Piscataway  substage. 

Length,  60  mm.;  height,  50  mm. 

Occurrence. — Aquia  Formation.  Aqnia  Creek,  Glymont,  Eeedy  Kun, 
Brooks  Estate  near  Seat  Pleasant,  Potomac  Creek,  Liverpool  Point,  Mat- 
tawoman  Creek. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
Philadelphia  Academy  of  Natural  Sciences. 

Crassatellites  ALTA  (Conrad). 

Plate  XLII,  Fig.  3. 

Crassatella  alia  Conrad,  1832,  Fossil  Shells  of  the  Tertiary,  No.  2,  p.  21,  pi.  vii. 

Crassatella  alia  Conrad,  1835,  Trans.  Geol.  Soc.  Penn.,  vol.  i,  p.  335. 

Description. — Snboval,  thick  and  ponderous,  compressed;  anterior 
margin  obtusely  rounded;  posterior  margin  broad  and  slightly  angular; 
beaks  with  regular  concentric  grooves,  and  somewhat  angnlated  behind; 
inner  margin  crennlated.^^  Conrad,  1832. 

Conrad  recorded  this  species  from  Upper  Marlboro  in  1835,  but  there 
is  no  other  evidence  of  its  occurrence  at  that  locality.  The  large  speci- 
men here  figured  is  from  Hardesty  and  can  belong  to  no  other  known 
species.  The  large  forms  alluded  to  under  C.  alaeformis  may  be  the 
same  as  the  Upper  Marlboro  forms  which  Conrad  referred  to  C.  alta. 

Length  (of  fragment),  105  mm.;  width,  75  mm. 

Occurrence. — Aquia  Formation.  Hardesty. 

Collection. — Maryland  Geological  Survey. 


MARYLAND  GEOLOGICAL  SURVEY 


183 


Crassatellites  sp. 

Plate  XLII,  Figs.  4,  4a. 

The  specimen  figured  possesses  characters  very  different  from  any 
other  known  species  of  the  genns  and  if  normal  mnst  he  new,  although  it 
is  perhaps  only  a diseased  specimen  of  C.  alaeformis. 

Length,  20  mm.;  width,  13  mm. 

Occurrence. — Aquia  Formation.  Clifton  Beach. 

Collection. — Johns  Hopkins  University. 

Family  ASTARTIDAE. 

Genus  ASTARTE  Sowerby. 

Astarte  marylandica  Clark. 

Plate  XLII,  Fig.  5. 

Astarte  marylandica  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xy,  p.  5. 

Astarte  marylandica  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  80,  pi.  xxi,  flg.  2. 

Description. — Shell  small,  ronndedly  trigonal,  somewhat  compressed, 
thick,  nearly  equilateral;  surface  concentrically  costated  and  with  super- 
imposed fine  striae;  nmhones  prominent.^’  Clark,  1896. 

Length,  16  mm.;  width,  15  mm. 

Occurrence. — Aquia  Formation.  Upper  Marlboro,  Brooks  Estate 
near  Seat  Pleasant,  SheckeFs  Farm  near  South  Elver. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

Family  PLEUROPHORIDAE. 

Genus  CORALLIOPHAGA  Blainville. 

Subgenus  ORYCTOMYA  Dali. 

CORALLIOPHAGA  (Oryctomya)  bryani  Clark. 

Plate  XLIII,  Figs.  1,  la,  2,  2a. 

Coralliophaga  hryani  Clark,  189.5,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 
Coralliophaga  hryani  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  73,  pi.  xv,  figs. 
2a,  26. 

Description. — “ Shell  transversely  oblong,  thin,  slightly  gaping  pos- 
teriorly; prominent  fold  from  umbo  to  lower  margin;  surface  with  deli- 


184 


SYSTEMATIC  PALEONTOLOGY 


cate  lines  of  growth  and  fine  radial  rows  of  minute  grannies,  obsolete 
over  mnch  of  the  surface;  teeth  consisting  of  two  small  cardinal  and 
one  long  posterior  lateral;  pallial  line  with  shallow  sinus/^  Clark,  1896. 

Only  two  specimens,  both  right  valves,  have  been  found.  The  one 
here  newly  figured  is  smaller  than  the  type,  but  more  nearly  perfect. 
The  teeth  are  not  well  preserved,  but  the  radiating  rows  of  grannies 
show  the  generic  affinities. 

Length,  20  mm.;  height,  16  mm. 

Occurrence. — Aquia  Formation.  1 mile  southeast  of  Mason  Springs, 
Pomonkey  Neck. 

Collections. — Maryland  Geological  Survey,  U.  S.  National  Mnsenm. 

Order  ANOM ALODESM ACEA. 

Family  PERIPLOMIDAE. 

Genus  PERIPLOMA  Schumacher. 

Periploma  (?)  sp. 

Two  specimens  have  been  found  which  have  the  general  form  of  this 
genns,  but  are  too  imperfect  for  complete  identification  or  description. 

Length,  29  mm.;  height,  24  mm. 

Occurrerice. — Nanjemoy^  Formation.  East  of  Port  Tobacco,  Wood- 
stock. 

Collections. — Maryland  Geological  Survey,  Philadelphia  Academy  of 
Natural  Sciences  (No.  6430). 

Family  PHOLADOMYIDAE. 

Genus  PHOLADOMYA  Sowerby. 

Pholadomya  marylandica  Conrad. 

Plate  XLIII,  Fig.  3. 

Pholadomya  marylandica  Conrad,  1843,  Proc.  Nat.  Inst.  Bull,  ii,  p.  193,  pi.  i,  fig.  3. 

Pholadomya  marylandica  Conrad,  1846,  Amer.  Jour.  Sci.,  ser.  ii,  vol.  i,  p.  214, 
pi.  ii,  fig.  9. 

Pholadomya  marylandica  IT.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  104. 

Pholadomya  marylandica  Conrad,  186.5,  Amer.  Jour.  Conch.,  vol.  i,  p.  3. 

Pholadomya  marylandica  Conrad,  1866,  Smith.  Misc.  Coll.  (300),  p.  8. 

Pholadomya  marylandica  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Pholadomya  marylandica  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  75,  pi.  xxix,. 
fig.  3. 


MAKYLAND  GEOLOGICAL  SUKVEY 


185 


Description. — OA^ate,  profoundly  ventricose,  with  coarse,  irregular 
concentric  lines  and  furroAvs,  and  obsolete,  rather  distant,  radii;  sum- 
mit of  umbo  prominent/’  Conrad,  1812. 

The  very  fragile  shell  of  this  species  Avas  found  only  partially  pre- 
serA^ed  in  a feAv  instances,  although  numerous  casts  Avere  obtained  from 
the  indurated  layer.  Zone  5,  at  Aquia  Creek. 

Length,  75  mm.;  height,  55  mm. 

Occurrence. — Aquia  Fokaiation.  Clifton  Beach  (upper  indurated 
bed),  Aquia  Creek,  Fort  Washington,  PiscataAAmy  (Conrad). 

Collections. — Maryland  Geological  Survey,  Philadelphia  Academy  of 
Xatural  Sciences,  Johns  Hopkins  University,  U.  S.  National  Museum. 

Order  PRIONODESMACEA. 

Family  MYTILIDAE. 

Genus  MODIOLUS  Lamarck. 

Modiolus  alabaaiensis  Aldrich. 

Plate  XLIII,  Figs.  4,  5,  5a. 

Jfodiola  alabamensis  Aldrich,  1895,  Bull.  Amer.  Pal.  No.  y,  p.  16,  nl.  v,  fig.  13. 

Modiola  poto7nacensis  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Jlodiola  potomaceiisis  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  85,  pi.  xxxiv, 
figs,  la-lc. 

Modiolus  {Bi'ccchijdontes)  potomacensis  Dali,  1898,  Trans.  AVagner  Free  Inst.  Sci.,  vol. 
iii,  pt.  iii,  p.  796. 

Description. — Shell  strongly  arcuate,  surface  with  raised  lines  closely 
set,  becoming  nearly  obsolete  on  the  beaks;  a few  lines  of  growth  cross- 
ing the  striae;  beak  small,  hinge  margin  slightly  curved,  ascending;  very 
small  fissure  on  basal  margin.”  Aldrich,  1895. 

Shell  small,  oblong,  thin,  tumid,  anterior  side  someivliat  contracted; 
surface  Avith  fine  costated  striae  nearly  obsolete  anteriorly  and  less 
strongly  accentuated  posteriorly  than  in  the  center,  crossed  occasionally 
by  irregular  lines  of  growth;  umbones  prominent,  curved. 

Length,  32  mm.;  width,  15  mm. 

Occurrence. — Xanjeaioy  Foraiation.  Popes  Creek,  Woodstock,  2.1 
miles  aboA^e  Popes  Creek.  Aquia  Foraiation.  Liverpool  Point,  Clif- 


186 


SYSTEMATIC  PALEONTOLOGY 


ton  Beach,  Wades  Bay,  Aqnia  Creek  (Zones  2 and  3),  Potomac  Creek,  2 
miles  below  Potomac  Creek,  Glymont,  1 mile  southeast  of  Mason  Springs, 
Upper  Marlboro,  Fort  Washington,  Month  of  Paspotansa  Creek. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
U.  S.  National  Museum,  Philadelphia  Academy  of  Natural  Sciences. 

Modiolus  makylandicus  n.  sp. 

Plate  XLIII,  Fig.  6. 

Description. — Shell  thin  and  fragile;  beaks  elevated,  strongly  incurved, 
and  situated  far  back  of  the  anterior  extremity;  surface  marked  by  strong 
lines  of  growth  and  faint  radiating  lines,  developing  into  strong  radial 
cracks. 

One  specimen  only,  and  that  showing  parts  of  both  valves,  has  been 
found;  while  another  that  may  belong  to  this  species,  although  it  shows 
some  quite  different  characteristics,  was  also  obtained. 

Length  (of  fragment),  20  mm.;  width,  10  mm. 

Occurrence. — Nanjemoy  Fokmation.  Woodstock. 

Collectio7i. — Maryland  Geological  Survey. 

Genus  LITHOPHAGA  Bolten. 

Lithophaga  makylandica  n.  sp. 

Plate  XLIII,  Fig.  7. 

Solemya  petricoloides  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Soleniya  petricoloides  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  74. 

Not  By ssomy a petricoloides  Lea. 

Description. — Shell  elongated,  very  inequilateral,  slightly  gaping, 
thin;  surface  nearly  smooth  tvith  fine  lines  of  growth;  umbones  very 
posteriorly  situated;  hinge  edentulous;  pallial  line  obscure.’^  Clark, 
1896. 

Our  specimens  differ  from  petricoloides  in  having  the  beaks  nearly 
terminal. 

Length,  11  mm.;  width,  4.5  mm. 

Occurrence. — Aquia  Formation.  Clifton  Beach. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  LBiiversity. 


MARYLAND  GEOLOGICAL  SURYEIT 


187 


Family  ANOMIIDAE. 

Genus  ANOMIA  Muller. 

Anomia  maeytlandica  n.  sp. 

Plate  XLIV,  Figs.  3,  3a,  3. 

Description. — Shell  small,  thin,  irregular;  valves  very  unequal;  right 
valve  moderately  and  uniformly  convex;  hyssal  opening  small;  left  valve 
very  convex  and  irregular.  Beak  anteriorly  situated  and  much  in- 
curved. Surface  marked  by  fine  raised  radiating  threads  and  irregular 
wavy  concentric  undulations.  Lines  of  growth  strong,  irregular. 

Length,  19.5  mm.;  height,  18  mm. 

Occurrence. — Xanjemoy  Formation.  Woodstock,  Popes  Creek. 
Aquia  Formation.  Clifton  Beach. 

Collection. — Maryland  Geological  Survey. 

Anomia  McGeei  Clark. 

Plate  XLIV,  Figs.  1,  la. 

(?)  Anomia  ruffini  Conrad,  1835,  Fossils  Medial  Tertiary,  p.  74,  pi.  xlii,  lig.  6. 

Aiiomia  mcgeei  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Anomia  mcgeei  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  86,  pi.  xxxiv,  figs. 

5a,  56. 

{?)  Anomia  ruffini  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  93. 

A7iomia  ruffini  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  pt.  iv,  p.  782. 

(In  part). 

Description. — Shell  of  left  valve  rather  solid,  convex,  nearly  equi- 
lateral; surface  strongly  lamellar,  with  faint  radial  plaits,  stronger  in 
the  latter  than  in  the  earlier  portions  of  the  shell.’^  Clark,  1896. 

The  type  of  this  species,  which  is  the  only  adult  specimen  known,  was 
found  in  the  collections  of  the  Philadelphia  Academy  of  Natural 
Sciences  labelled  “Eocene  of  Hanover  County,  Ya.’^  Anomia  ruffini 
Conrad  was  described  with  Miocene  fossils  (the  type  having  been  found 
on  the  Pamunkey  Eiver,  Virginia,  where  both  Eocene  and  Miocene 
strata  occur),  and,  was  later,  by  Conrad  and  by  others,  placed  in  lists  of 
both  Eocene  and  Miocene  forms.  It  is  extremely  doubtful  if  the  species 
has  ever  been  found  in  the  Eocene. 

The  resemblance  between  A.  mcgeei  and  A.  ruffini  is  so  close  and 
both  are  so  different  from  any  other  forms  which  have  ever  been  found 


188 


SYSTEMATIC  PALEONTOLOGY 


in  the  Eocene  that  it  is  possible  that  they  both  represent  the  same 
Miocene  species.  Dr.  Dali  considers  them  identical  but  is  in  donht  as 
to  the  horizon  from  which  they  came. 

It  seems  best  to  publish  here  the  original  figures  of  A.  mcgeei  under 
the  original  name  in  order  to  bring  the  question  before  the  eyes  of  future 
investigators. 

Length,  50  mm.;  height,  48  mm. 

Occurrence. — Hanover  County,  Ya. 

Collection. — Philadelphia  Academy  of  Natural  Sciences. 

Family  PECTINIDAE. 

Genus  PECTEN  Muller. 

Pecten  choctavensis  Aldrich. 

Plate  XLIV,  Pigs.  4,  5,  6. 

Fecten  choctavennis  Aldrich,  1895,  Bull.  Amer.  Pal.  No.  2,  p.  16,  pi.  v,  fig.  7. 

Description. — Shell  suhorhicular  thin,  depressed,  finely  closely  rib- 
bed, ribs  showing  through  the  substance  of  the  shell,  imbricated  near 
the  ventral  margin  and  on  the  anterior  slope;  ears  ribbed  and  ribs  im- 
bricated with  fine  oblique  reticulations  between.”  Aldrich,  1895. 

There  are  40  to  50  ribs,  which  are  lamellated,  especially  when  old, 
but  sometimes  when  very  young.  The  young  shells  from  Alabama  do 
not  show  any  lamellation.  The  ribs  increase  both  by  bifurcation  and 
intercolation.  Camptonectes  structure  is  a constant  characteristic. 

Width,  23  mm.;  height,  24  mm. 

Occurrence. — Nanjemoy  Fokmation.  Popes  Creek,  miles  above 
Popes  Creek.  Aquia  Formation.  Upper  Marlboro,  1 mile  northeast 
of  Piscataway,  South  East  Creek  (1  mile  from  Chester  Eiver). 

Collection. — Maryland  Geological  Survey. 

Pecten  dalli  Clark. 

Plate  XLIV,  Figs.  7,  7a,  7b. 

Pecten  rogersi  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Fecten  rogersi  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  85,  pi.  xxxiv,  figs.  2a-2c. 

Pecte7i  dalli  Clark,  1898,  Johns  Hopkins  Univ.  Circ.,  vol.  xviii,  p.  18. 

Fecteix  {Fsendamusinm)  frontalis  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii, 
pt.  iv,  p.  753. 

Not  FectcM  rogersi  Conrad. 


MAKYLAXD  GEOLOGICAL  SURVEY 


189 


Descri'ption. — Shell  small,  orbicular,  siibpellucid,  nearl}^  equilateral, 
thin;  surface  shining  with  fine,  delicate  concentric  lines  and  rather  ob- 
scure, in  places  obsolete,  radial  ribs  that  show  most  strongly  near  the 
anterior  margins;  umbones  approximate  and  acute;  auricles  very  un- 
equal and  costated/^  Clark,  1896. 

This  very  beautiful  species  shows  some  points  of  similarity  to  P.  cal- 
vatns  Conrad  in  form  and  surface  features,  but  the  radial  striae  are  lack- 
ing upon  the  latter.  It  differs  from  P.  choctavensis  in  its  feebler  sculp- 
ture. It  possesses  a faint  camptonectes  structure. 

Width,  16  mm.;  height,  18  mm. 

Occurrence. — Hanjemoy  Formation.  Woodstock,  Upper  Marlboro 
(deep  cut  near  Chesapeake  Beach  E.  E.  station).  Aquia  Forma- 
Tiox.  Potomac  Creek,  South  East  Creek  (1  mile  above  Chester  Eiver). 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

Pectex  johnsoni  Clark. 

Plate  XLIV,  Figs.  8,  8a. 

Pecten  johnsoni  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  i).  5. 

Pecten  johnsoni  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  j).  85,  pi.  xxxiv,  flgs. 

3fl[,  36. 

Description. — Shell  small,  suborbicular,  equilateral;  surface  with 
about  twenty  uniform,  distant,  rounded  costate,  separated  by  broad 
interspaces,  with  a few  short  costae  at  basal  margin,  the  whole  crossed 
by  fine  lines  of  growth;  ears  prominent,  unequal.^’  Clark,  1896. 

P.  greggi  Harris  resembles  this  form  very  closely.  It  differs  in  hav- 
ing stronger  camptonectes  structure,  and  in  not  having  the  number  of 
ribs  increase  toward  the  periphery. 

Width,  14  mm.;  height,  15  mm. 

Occurrence. — Haxjemoy  Formatiok.  AYoodstock.  Aquia  Forma- 
Tiox.  2 miles  below  Potomac  Creek,  Potomac  Creek,  Mouth  of  Paspo- 
tansa  Creek. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 


190 


SYSTEMATIC  PALEONTOLOGY 


Pecten  sp. 

Plate  XLIV,  Figs.  9^  9a. 

Pecten  sp.  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Pecten  sp.  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  86,  pi.  xxxiv,  fig.  4. 

Description. — Shell  small,  orbicular;  surface  with  about  twenty 
broad,  flat  costae,  dividing  in  most  cases  in  passing  downward,  so  that 
over  thirty  appear  at  the  margin;  umbones  compressed;  ears  unequal.^^ 
Clark,  1896. 

This  differs  from  P.  jolinsoni  only  in  having  the  ribs  increase  by 
bifurcation  instead  of  intercolation,  and  in  having  the  ribs  broader  than 
the  interspaces.  As  the  figured  specimen  is  the  only  one  that  has  been 
found  and  is  very  immature  it  is  best  not  to  give  it  a name.  Perhaps  it 
is  an  aberrant  or  immature  form  of  P.  jolinsoni,  or  of  P.  walitubheanus 
Dali. 

Width,  10  mm.;  height,  11  mm. 

Occurrence. — Aquia  Formation.  Potomac  Creek. 

Collection. — Maryland  Geological  Survey. 

Family  OSTREIDAE. 

Genus  OSTREA  Linne. 

OsTREA  compressirostra  Say. 

Plates  XLV,  XLVI,  XLVII. 

Ostrea  compressirostra  Say,  1824,  Jour.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  132,  pi.  viii, 
figs.  2a,  26  [Reprint  Bull.  Amer.  Pal.  No.  5,  p.  38,  pi.  viii,  figs.  2a,  26.] 

Ostrea  compressirostra  Morton,  1834,  Syn.  Org.  Rem.  Cretaceous  Group,  App.,  p.  2. 
Ostrea  smuosa  Rogers,  1837,  Trans.  Amer.  Philos.  Soc.,  vol.  v,  p.  340;  vol.  vi, 
pi.  xxvii,  fig.  1. 

Ostrea  compressirostra  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  103. 
Ostrea  hellovacina  Conrad,  1842,  Proc.  Nat.  Inst.,  Bull,  ii,  p.  172  (not  of  Lamarck). 
Ostrea  smuosa  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  103. 

Ostrea  compressirostra  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  15. 

Ostrea  sinuosa  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  15. 

Ostrea  compressirostra  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  3. 

Ostrea  compressirostra  Heilprin,  1883,  White’s  Fossil  Ostreidae ; Fourth  Ann.  Rept. 

U.  S.  Geol.  Survey,  p.  309,  pi.  Ixv,  figs.  1,  2. 

Ostrea  coynpressirostra  Heilprin,  1884,  Contrib.  Tert.  Geol.  and  Pal.,  p.  85. 

Ostrea  sinuosa  Rogers,  1884,  Geology  of  the  Virginias,  p.  668,  pi.  ii,  fig.  1. 

Ostrea  compressirostra  de  Gregorio,  1890,  Ann.  Geol.  et  Pal.,  t.  ii,  p.  177,  pi.  xx, 
figs.  1,  8. 


MARYLAND  GEOLOGICAL  SURVEY 


191 


Ostrea  compressiroslra  Harris,  1894,  Amer.  Jour.  Sci.,  ser.  iii,  vol.  xlvii,  p.  302. 

Ostrea  compressirosira  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Ostrea  comprensirostra  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  86,  pi.  xxxvii, 
figs.  1,  2tt-2c;  pi.  xxxviii,  figs,  la,  16,  2a-2c;  pi.  xxxix,  figs.  1,  2a,  26;  pi.  xl, 
flg-  1- 

Ostrea  compressirosira  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  pt.  iv, 
p.  679. 

Description. — Shell  sinistral;,  siibovate:  inferior  valve  convex,  with 
iiiiineroiis  convex  ribs  interrupted  by  fornicated  scales  at  the  lines  of 
increment;  hinge  curving  a little  upward,  very  mnch  contracted  and 
short:  superior  valve  flat,  wrinkled  concentrically,  without  any  appear- 
ance of  longitudinal  lines:  hinge  more  dilated  than  that  of  the  superior 
valve,  and  oblique  with  respect  to  the  thickness  of  the  shell/^  Say, 
1824. 

This  is  one  of  the  most  abundant  fossils  in  the  Aquia  formation.  The 
Xanjemoy  formation  contains  many  small  oysters  which  are  probably 
the  young  of  sellaeformis,  although  they  cannot  be  distinguished  from 
the  young  of  this  species. 

Length,  215  mm.;  width,  180  mm. 

Occurrence. — Aquia  Formation.  Upper  Marlboro,  Hardesty,  Aquia 
Creek,  Brooks  Estate  near  Seat  Pleasant,  3 miles  west  of  Leeland  on 
Western  Branch,  SheckeFs  Farm  near  South  Eiver,  Keedy  Kun,  Liver- 
pool Point,  IJ  miles  south  of  Grimesville,  Potomac  Creek,  Fort  Wash- 
ington, Tinkers  Creek,  1 mile  northeast  of  Piscataway,  Swan  Creek 
(ravine  near  Piscataway  Creek),  1 mile  southeast  of  Mason  Springs, 
Mouth  of  Paspotansa  Creek,  Wades  Bay,  3 miles  west  of  Pisgah,  Clifton 
Beach,  Mattawoman  Creek,  2 miles  south  of  South  Eiver,  Glymont,  2 
miles  below  Potomac  Creek,  Leeland,  Seven  Eiver. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
U.  S.  Xational  Museum,  Philadelphia  Academy  of  Xatural  Sciences. 

Ostrea  compressirostra  var.  alepidota  Dali. 

Ostrea  compressirostra  var.  alepidota  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.,  vol. 
iii,  part  iv,  p.  680. 

Description. — AVithout  raised  lamellae  externally  but  with  radial 
grooves.^^  Dali,  1898. 


192 


SYSTEMATIC  PALEONTOLOGY 


Shell  small^  roughly  triangular;  beak  high,  in  some  cases  slightly 
twisted;  raised  lamellae  absent  or  confined  to  the  extreme  periphery; 
radial  grooves,  becoming  stronger  toward  the  periphery. 

Length,  85  mm.;  width,  65  mm. 

Occurrence. — Aquia  Formation.  Fort  Washington,  Aquia  Creek. 

Collections. — Maryland  Geological  Survey,  V.  S.  National  Museum, 
Philadelphia  Academy  of  Natural  Sciences. 

OsTREA  SELLAEFORMis  Conrad. 

Plates  XLVIII,  XLIX. 

Ostrea  sellaeformis  Conrad,  1832,  Fossil  Shells  of  the  Tertiary,  No.  2,  p.  27,  pi.  xiii, 
fig.  2. 

Ostrea  sellaeformis  Morton,  1834,  Syn.  Org.  Rem.  Cretaceous  Group,  App.,  p.  6. 

Ostrea  sellaeformis  Conrad,  1842,  Proc.  Nat.  Inst.,  Bull,  ii,  pp.  192,  193,  pi.  i,  fig.  1. 

Ostrea  sellaeformis  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  103. 

Ostrea  sellaeformis  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  15. 

Ostrea  sellaeformis  Conrad,  Smith.  Misc.  Coll.  (200),  p.  3. 

Ostrea  sellaeformis  1883,  White’s  Fossil  Ostreidae  ; Fourth  Ann.  Rept. 

U.  S.  Geol.  Survey,  p.  311,  pi.  Ixii,  figs.  1,  2 ; pi.  Ixiii,  fig.  1. 

Ostrea  sellaeformis  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Ostrea  sellaeformis  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  87,  pi.  xxxv,  figs. 
la-l(Z;  pi.  xxxvi,  figs,  la,  16. 

Description. — Oblong,  convex,  thick  and  ponderous,  lohed;  one  side 
of  the  larger  valve  profoundly  sinuous  and  the  opposite  side  gibbous; 
smaller  valve  sinuous  and  little  convex;  dorsal  margin  long  and  slightly 
arched,  with  both  extremities  obtusely  rounded.”  Conrad,  1833. 

This  form  although  very  abundantly  and  characteristically  developed 
in  the  valleys  of  the  James  and  Pamunkey  rivers,  occurs  generally  in 
the  Potomac  Valley  and  farther  north  only  as  small  specimens,  almost 
indistinguishable  from  the  young  of  0.  compressirostra. 

Height,  60  mm.;  width,  40  mm.  (largest  Maryland  specimen). 

Occurrence. — Nanjemoa^  Formation.  Popes  Creek,  1-J  miles  above 
Popes  Creek,  2J  miles  above  Popes  Creek,  East  of  Port  Tobacco,  Upper 
Marlboro  (deep  cut  near  Chesapeake  Beach  B.  E.  station),  Woodstock. 

Collections. — Johns  Hopkins  University,  Philadelphia  Academy  of 
Natural  Sciences,  Maryland  Geological  Survey. 


MAKYLAXD  GEOLOGICAL  SUKVEY 


193 


Subgenus  GRYPH AEOSTREA  Conrad. 

OSTREA  (GrYPHAEOSTREA)  TOMER  (Mortoil). 

Plate  Figs.  1,  la,  lb,  2,  3,  4,  4a,  5. 

Gryphaea  vomer  Morton,  1830,  Jour.  Acad.  Nat.  Sci.  Pliila.,  vol.  vi  (1st  series),  p.  83, 

Gryphaea  vomer  Morton,  1834,  Syn.  Org.  Rem.  Cretaceous,  p.  54,  pi.  ix,  tig.  5. 

Gryphaea  vomer  Conrad,  1835,  Trans.  Geol.  Soc.  Penn.,  a^oI.  i,  p.  336. 

Gryphaea  vomer  Conrad,  1842,  Proc.  Nat.  Inst.,  Bull,  ii,  p.  172. 

Ostrea  {Gryphaeostrea)  subeversa  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  1,  p.  15 
(name  only). 

Ostrea  sp.  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  6. 

Ostrea  sp.  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  88,  pi.  xxxix,  tigs.  3a-3c. 

Ostrea  subeversa  Clark,  1896,  Bull.  141,  U.  S.  Geol,  Survey,  p.  93. 

Ostrea  {Gryphaeostrea)  subeversa  Dali,  1898,  Trans.  Wagner  Free  lust.  Sci.,  vol.  iii, 
pt.  iv,  p,  681. 

Description. — “ Oblong-oval,  thin,  narrow;  lower  valve  deep,  longi- 
tudinally curved;  beak  prominent,  curved  laterally;  upper  valve  small  in 
proportion  to  the  lower,  and  marked  with  distinct,  concentric,  squamose 
plates  ” Morton,  1834. 

The  possible  equivalence  of  this  form  with  Gryphaea  vomer  Morton, 
or  Gryphaea  eversa  Mellville  was  suggested  by  Dali.  Conrad  recorded 
the  species  from  Piscataway  and  Upper  Marlboro. 

Length,  39  mm.;  width,  20  mm.;  depth  of  lower  valve,  10  mm. 

Occurrence. — Nanjemoy  Formation.  mile  below  Chapel  Point. 
Aquia  Formation.  Piscataway,  Upper  Marlboro,  Aquia  Creek,  Po- 
tomac Creek,  2 miles  below  Potomac  Creek,  Sheckel’s  Farm  near  South 
River,  Fredericktown,  Glymont. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
Philadelphia  Academy  of  Natural  Sciences. 

Genus  GRYPHAEA  Lamarck. 

Gryphaea  vesicularis  Lamarck. 

Plate  L,  Figs.  6,  6a. 

Gryphaea  vesicularis  Lamarck,  1806,  Ann.  Mus.  viii,  p.  160,  pi.  xxii,  flg.  3.  An. 
Sans.  Vert.,  vol.  vi,  p.  209. 

A single  specimen  of  this  form  was  found  associated  with  Eocene 
fossils  at  Clifton  Beach.  It  is  very  perfect,  having  both  valves  in  posi- 
tion. It  seems  hardly  possible,  however,  that  it  can  be  a representative 
13 


194 


SYSTEMATIC  PALEONTOLOGY 


of  the  Eocene  fauna,  as  an  isolated  specimen  of  this  typical  Cretaceous 
species,  it  seems  more  probable  that  it  must  have  been  derived  from 
Cretaceous  deposits.  An  even  more  remarkable  occurrence  is  the  dis- 
covery of  many  specimens  of  Terebratula  liarlani  under  similar  condE 
tions  (see  p.  204). 

Occurrence. — Aquia  Eoemation.  Clifton  Beach. 

Collection. — Maryland  Geological  Survey. 

Family  PTERIIDAE. 

Genus  PTERIA  Scapoli. 

Pteria  limula  (Conrad). 

Plate  LI,  Fig.  1. 

Avicula  limula  Conrad,  1833,  Fossil  Shells  of  the  Tertiary,  No.  4,  p.  39. 

Description. — Shell  convex,  with  slight  concentric  undulations; 
umbo  tapering  gradually  towards  the  apex,  which  is  acute,  but  not 
prominent;  wings  large  and  very  oblique;  sinus  of  the  posterior  margin 
not  profound;  nacre  very  pearly  and  iridescent.  Height,  inches.’^ 
Conrad,  1833. 

Height  of  largest  fragment,  18  mm. 

Occurrence. — Hanjemoy  Formation.  Popes  Creek,  Hills  Bridge. 
Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Family  ARCIDAE. 

Genus  GLYCYMERIS  Da  Costa. 

Glycymeris  idoneus  (Conrad). 

Plate  LI,  Figs.  2,  2a,  3,  3a,  4. 

Pectunciilas  idoneus  Conrad,  1833,  Fossil  Shells  of  the  Tertiary,  No.  4,  p.  39. 

Pectanculus  idoneus  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Peciunculus  idoneus  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  84,  pi.  xxix,  figs, 
la-lc,  2. 

Description. — Shell  suborbicular,  thick,  convex;  oblique,  with  rather 
obscure  radiating  striae,  and  very  minute,  intervening  lines;  umbo  con- 
vex; beaks  distant,  rather  prominent  and  pointed;  cardinal  teeth  large; 


MARYLAND  GEOLOGICAL  SURVEY 


195 


truncated  in  the  center  by  a rectilinear  line;  cavity  capacious;  margin 
crenate.  Length,  in  ” Conrad,  1833. 

Shell  moderately  thick,  obliquely  orbicular,  rather  ventricose,  slightly 
inequilateral,  equivalve,  with  faint  radiations;  hinge  with  few  promi- 
nent teeth;  margins  crenulated;  beaks  depressed. 

The  higher  beds  of  the  Aquia  formation,  especially  the  indurated 
ledge  at  Upper  Marlboro  and  at  the  localities  to  the  northeast,  are  very 
rich  in  shells  of  Glycymeris.  Although  in  some  features  they  at  times 
show  slight  variations  from  G.  idoneus  of  the  Gulf,  the  differences  are 
too  slight  to  warrant  specific  distinction. 

Length,  60  mm.;  height,  60  mm. 

Occurrence. — Xanjemoy  Formation.  3 miles  above  Popes  Creek, 
AYoodstock.  Aquia  Formation.  Upper  Marlboro,  1 mile  west  of 
Hardesty,  Potomac  Creek,  1 mile  northeast  of  Piscataway,  Hardesty, 
Sheckels  Farm  near  South  Eiver,  2 and  3 miles  south  of  South  Eiver, 
Eolph’s  Landing. 

Collections. — Philadelphia  Academy  of  Xatural  Sciences,  Johns  Hop-  • 
kins  University,  Maryland'  Geological  Survey. 

Family  LIMOPSIDAE. 

Genus  TRIGONOARCA  Conrad. 

Trigonoarca  decisa  (Conrad)  var. 

Plate  LI,  Figs.  5,  5a. 

Pectunculns  decisus  Conrad,  1833,  Fossil  Shells  of  the  Tertiary,  p.  39. 

Limopsis  decisus  Conrad,  1860,  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  ser.,  vol.  iv,  p.  297, 
pi.  xlvii,  fig.  13. 

(?)  Noetia  pulchra  Gahb,  1860,  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  ser.,  vol.  iv, 
p.  388,  pi.  Ixvii,  fig.  65. 

Trigonoarca  pulchra  var.  Harris,  1897,  Bull.  Amer.  Pal.  No.  9,  p.  48,  pi.  viii,  figs. 
2,  2a. 

Description. — Shell  longitudinally  suhoval,  equilateral,  with  obsolete 
radiating  striae;  posterior  end  obliquely  truncated,  umbonial  slope  angu- 
lated,  incurved;  beaks  small,  pointed  and  recurved;  cardinal  teeth  small 
and  crowded;  series  not  much  arcuated;  margin  entire.  Length,  J of  an 
inch.^’  Conrad,  1833. 

This  form  is  smaller  and  proportionally  longer  than  T.  pulchra  Gahb 


196 


SYSTEMATIC  PALEONTOLOGY" 


and  has  fainter  sculpture.  It  is  much  more  like  the  variety  figured  by 
Harris. 

Length,  4 mm.;  width,  2.5  mm. 

Occurre7ice. — Nanjemoy"  Fokmation.  Woodstock. 

Collection. — Maryland  Geological  Survey. 

Family  PARALLELODONTIDAE. 

Genus  CUCULLAEA  Lamarck. 

CucuLLAEA  GiGANTEA  Conrad. 

Plates  LII,  LIII,  LIV,  LV. 

Cucnllaea  qigmitea  Conrad,  1830,  Jour.  Acad.  Nat.  Sci.  Phila.,  vol.  vi,  p.  227,  pi.  x, 
tig.  4. 

Cucullaea  onochela  Roi^ers,  1839,  Trans.  Amer.  Philos.  Soc.,  vol.  vi,  p,  372,  pi. 
xxviii,  fig.  2. 

Cucullaea  transversa  Rogers,  1839,  Trans.  Amer.  Philos.  Soc.,  vol.  vi,  p.  373,  pi. 
xxix,  fig,  1. 

Cucullaea  gigantea  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  98. 

Cticullaea  onochela  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  98. 

Cucullaea  transverm  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  98. 
Cucullaea  rogersiana  Nyst,  1848,  Tabl.  Synopt.  Arcacees,  p.  63. 

Latiarca  gigantea  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  11. 

Latiarca  onochela  Conrad,  1865,  Amer.  Jour.  Conch.,  vol,  1,  p.  11. 

Latiarca  transversa  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  11. 

Latiarca  gigantea  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  4. 

Latiarca  onochela  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  4. 

Latiarca  transversa  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  4. 

I^atiarca  idonea  Conrad,  1872,  Proc.  Acad.  Nat.  Sci.  Phila.,  p.  53,  pi.  ii,  fig.  1. 

Area  rogersi  Heilprin,  1881,  Proc.  Acad.  Nat.  Sci.  Phila.,  p,  449. 

Cucullaea  onochela  Rogers,  1884,  Geology  of  the  Virginias,  p.  669,  pi.  iii,  fig.  2. 
Cucullaea  transversa  Rogers,  1884,  Geology  of  the  Virginias,  p.  670,  pi.  iv,  fig.  1. 
Area  onochela  Heilprin,  1884,  Contrib.  Tert.  Geol.  and  Pal.,  p.  87. 

Cucullaea  transversa  Harris,  1894,  Amer.  Jour.  Sci.,  ser.  iii,  vol.  xlvii,  p.  302. 
Cucullaea  gigantea  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Cucullaea  gigantea  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  84,  pi.  xxx,  xxxi, 
xxxii,  xxxiii. 

Cucullaea  gigantea  var.  Harris,  1897,  Bull.  Amer.  Pal.  No.  9,  p.  49,  pi.  viii,  figs. 
3a,  4. 

Cucullaea  gigantea  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  pt.  iv,  p.  603. 
Cucullaea  transversa  Dali,  1898,  Trans.  Wagner  Free  Inst.  Sci.,  vol.  iii,  pt.  iv,  pp. 
603,  646. 

Description. — Shell  subtriangular,  obliquely  cordate;  very  ventri- 
cose,  with  numerous  longitudinal  sulci;  anterior  side  flattened,  produced 


MARYLAND  GEOLOGICAL  SURVEY" 


197 


and  snbcnneiform;  posterior  side  very  short;  umbones  gibbous;  beaks 
distant  and  much  incurved.*^  Conrad,  1830. 

A careful  examination  of  the  various  forms  of  Cucullaea  from  the 
Maryland  and  Virginia  Eocene  shows  them  to  be  modifications  of  a 
single  species  that  possesses  great  variability  in  outline  and  surface 
decoration.  The  most  profound  changes  appear  upon  comparison  of 
3’oung  and  adult  forms.  The  immature  shells  are  relatively  not  as  high 
or  as  tumid  and  possess  much  narrower  ligament  areas  than  the  adults. 
Kogers  gave  the  name  of  C.  transversa  to  these  young  forms.  Casts  of 
tlie  larger  shells  are  not  uncommon  and  are  locally  known  as  ^Aurtle 
heads.’^ 

Professor  Harris  agrees  with  us  in  regarding  the  Maryland-Yirginia 
Cucullaeas  as  all  of  one  species,  and  also  includes  in  it  a form  from  the 
Chickasawan  of  Alabama  of  the  transversa  type.  Dr.  Dali,  however, 
recognizes  two  species.  If  it  were  possible  to  separate  the  forms  the  dis- 
tinction between  the  gigantea  and  transversa  types  would  be  very  useful, 
since  the  former  occurs  only  in  the  Aquia  formation,  while  the  latter 
is  the  only  form  found  in  the  Hanjemoy  formation  or  in  the  Gulf  states. 

Occurrence. — Xaxjemoy"  Formation.  Popes  Creek,  Woodstock, 
Thrift  (well).  Aquia  Formation.  Liverpool  Point,  1 mile  southeast 
of  Mason  Springs,  Potomac  Creek,  Paspotansa  Creek,  2 miles  below  Po- 
tomac Creek,  Aquia  Creek,  Clifton  Beach,  1 mile  northeast  of  Piscata- 
way.  Upper  Marlboro,  Hardesty,  Eolph’s  Landing,  3 miles  west  of 
Leeland,  Fort  Washington,  Glymont,  SheckeFs  Farm  near  South  Eiver, 
Fredericktown  (?). 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University, 
U.  S.  Xational  Museum,  Philadelphia  Academy  of  Hatiiral  Sciences. 

Led  A PARVA  (Eogers). 

Plate  LVI,  Figs.  5,  6,  7,  7a. 

Xacula  parva  Rogers,  1837,  Trans.  Amer.  Philos.  Soc.,  vol.  v,  p.  840.  (Reprint 
Geology  of  the  Virginias,  1884,  p.  668.) 

Xacula  parva  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.,  Phila.,  vol.  iv,  p.  102. 

Leda  parva  Conrad,  1854,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  vii,  p.  29. 

Xaculana  parva  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  3. 

Xuculana  parva  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  3. 

Lecla  parva  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Leda  parva  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  83,  pi.  xxviii,  figs.  2a-2d 


198 


SYSTEMATIC  PALEONTOLOGY 


Description. — Shell  ovate,  inflated,  rounded  before,  not  much  pro- 
duced, but  rapidly  tapering  to  a truncated  point  behind,  furnished  with 
about  twelve  rather  coarse  concentric  folds  or  ridges,  and  a longitudinal 
gently  depressed  groove  or  undulation  of  surface,  running  from  near 
the  beak  to  the  posterior  basal  margin;  beaks  nearly  central;  anterior 
series  of  teeth  slightly  arched;  posterior  series  nearly  straight;  margin 
entire;  cavity  rather  deep/^  Kogers,  1837. 

Length,  5 mm.;  height,  3 mm. 

Occurrence. — Nanjemoy  Fokmation.  Popes  Creek,  Woodstock, 
miles  above  Popes  Creek. 

Collections. — Philadelphia  Academy  of  Natural  Sciences,  Johns  Hop- 
kins University,  Maryland  Geological  Survey. 

Leda  cultellieokmis  (Rogers). 

Plate  LVI,  Figs.  8,  8a. 

Nucula  cultelliformis  Rogers,  1837,  Trans.  Amer.  Philos.  Soc.,  new  series,  vol.  v, 
p.  339. 

Nucula  cultelliformis  H.  C.  Lea,  1848,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iv,  p.  102. 

Leda  cultelliformis  Conrad,  1854,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  vii,  p.  29. 

Nuculana  cultelliformis  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  13. 

Nuculana  cultelliformis  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  3. 

Nucula  cultelliformis  Rogers,  1884,  Geology  of  the  Virginias,  p.  667. 

Yoldia  cultelliformis  Clark,.  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Leda  {Adrana)  cultelliformis  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  83,  pl_ 
xxviii,  ligs.  3a,  35. 

Description. — Shell  ovate,  ensifgrm,  somewhat  inflated,  rounded  be- 
fore, much  elongated  and  tapering  behind,  the  posterior  length  more 
than  twice  the  anterior,  furnished  with  very  fine,  hardly  distinct  concen- 
tric striae,  and  one  distinct  and  one  very  obscure  rib  behind;  anterior 
part  with  an  indistinct  fold;  shell  thin;  lunule  long  and  lanceolate;  beak 
small;  anterior  series  of  the  teeth  gently  arched;  posterior  series  straight; 
teeth  in  both  acutely  bent,  the  angles  directed  toward  the  beak;  margin 
entire;  cavity  of  shell  shallow,  with  a ridge  passing  from  the  beak  to  the 
posterior  margin.^^  Rogers,  1837. 

Length,  10  mm.;  height,  4 mm. 

Occurrence. — Aquia  Formation.  Clifton  Beach.  Nanjemoy'  For- 


MAKYLAXD  GEOLOGICAL  SURVEY 


199 


MATiox.  Popes  Creek,  miles  above  Popes  Creek,  Woodstock,  Upper 
Marlboro  (deep  cut  near  Chesapeake  Beach  E.  R.  station). 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

Family  LEDIDAE. 

Genus  LEDA  Schumacher. 

Led  A IMPROCERA  (Conrad). 

Plate  LVI,  Figs.  1,  2,  3,  4. 

Nucula  improcera  Conrad,  1848,  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  ser.,  vol.  i,  p.  131, 
pi.  xiv,  fiff.  23. 

Nuculana  improcera  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  13. 

Nxiculana  improcera  Conrad,  1866,  Smith.  Misc.  Coll.  (200),  p.  3. 

Leda  improcera  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Leda  improcera  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  83,  pi.  xxviii,  figs. 
la-ld  (not  Ic). 

Description. — Elongate,  very  inequilateral,  convex,  polished,  and 
having  fine  indistinct  concentric  lines;  anterior  side  produced,  bicarin- 
ated;  the  upper  margin  incurved  toward  the  apex;  extremity  angulated.” 
Conrad,  1848. 

This  species  shows  considerable  variation  in  outline.  Conrad’s  types 
are  of  the  more  elongate  form.  If  the  more  elevated  form  is  a con- 
stant variation  it  should  be  separated  as  a new  variety  or  species. 

Length,  8 mm.;  height,  4 mm.  (typical).  Length,  11  mm.;  height,  7 
mm.  (elevated  form). 

Occurrence. — Hanjemoy  Formation.  Popes  Creek,  Woodstock, 
Head  of  Hanjemoy  Creek,  2J  miles  above  Popes  Creek. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

Leda  parilis  (Conrad). 

Plate  LVII,  Figs.  1,  2,  2a. 

Nucula  parilis  Conrad,  1848,  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  ser.,  vol.  i,  p.  132, 
pi.  xiv,  fig.  31. 

Nucula  parilis  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  93. 

Description. — Ovate,  ventricose,  with  concentric  lines;  beaks  medial; 
anterior  end  pointed,  angular;  posterior  end  regularly  rounded;  an- 
terior submargin  carinated,  hinge  margin  very  oblique,  straight  from 


200 


SYSTEMATIC  PALEONTOLOGY 


the  apex,  except  near  the  end  where  it  is  somewhat  angnlated.”  Con- 
rad, 1848. 

This  very  distinct  species  has  been  found  only  in  and  immediately 
above  the  indurated  ledge  at  Upper  Marlboro  and  Sonth  River  bridge. 
It  is  rare  in  the  indurated  ledge  but  abundant  in  the  shell  bed  imme- 
diately above  it.  The  type  which  came  from  Upper  Marlboro  is  still  in 
the  collection  of  the  Philadelphia  Academy  of  Uatnral  Sciences. 

Length,  15  mm.;  height,  9 mm. 

Occurrence. — Aquia  Foemation.  Upper  Marlboro,  Sheckel’s  Farm 
near  Sonth  River. 

Collections. — Maryland  Geological  Survey,  Philadelphia  Academy  of 
Uatnral  Sciences. 

Leda  paeilis  vae. 

Plate  LVII,  Fig.  3. 

Leda  improcera  Clark,  Bull.  141,  U.  S.  Geol.  Survey,  pi.  xxviii,  fig.  1e. 

This  form  is  a connecting  link  between  L.  cliftonensis  and  L.  parilis 
and  might  be  the  descendant  of  either.  It  is  less  globose  and  has 
smaller,  more  nnmerons  folds  than  L.  parilis;  and  is  somewhat  more 
elevated  than  L.  cliftonensis  with  smaller,  more  closely-set  folds. 

Length,  11  mm.;  width,  6.5  mm. 

Occurrence. — Uanjemoy  Foemation.  Hills  Bridge,  Woodstock. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University. 

Leda  potomacensis  n.  sp. 

Plate  LVI,  Figs.  9,  10. 

(.^)  Nuculana  protexla  Conrad,  1865,  Amer.  Jour.  Conch.,  vol.  i,  p.  147,  pi.  xi,  fig.  6. 

(In  part.) 

Leda  protexla  Clark,  1895,  Johns  Hopkins  Unix.  Circ.,  vol.  xv,  p.  5. 

Leda  protexta  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  82. 

Description. — Shell  large,  transverse,  elongate,  anterior  side  round- 
ed, posterior  somewhat  longer,  attenuated,  terminating  in  an  obtuse 
beak;  surface  with  numerous  concentric  striations  somewhat  interfered 
with  on  the  rostrated  portion  of  the  posterior  side,  where  the  riblets 
become  more  lamellated  and  wavy  and  at  times  even  disappear.’^  Clark, 
1896. 


MARYLAND  GEOLOGICAL  SURVEY 


201 


Xiicnlana  protexta  Conrad  (1865),  which  is  Leda  protexta  Harris 
(189T),  includes  two  forms.  The  first  has  been  described  by  Dr.  Dali 
as  Leda  pliarcida  and  occurs  at  Wood's  Bluff,  Choctaw  Corner,  and  Cave 
Branch,  x\la.  The  second,  which  is  Leda  protexta  Clark  (1896),  is 
described  here,  and  occurs  outside  of  Maryland  at  Bell’s  Landing,  Gregg’s 
Landing,  and  Yellow  Bluff,  Ala.  The  above  localities  are  all  given 
from  material  in  the  collection  of  the  Philadelphia  Academy  of  Yatnral 
Sciences. 

Length,  37  mm.;  width,  17  mm. 

Occurrence. — Yaxjemoy  Formation.  Woodstock,  West  of  Port  To- 
bacco, 1 mile  southeast  of  Piscataway,  ^ mile  below  Chapel  Point, 
Charles  Branch  between  Eosary ville  and  Upper  Marlboro,  Popes  Creek. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

Leda  cliftonensis  n.  sp. 

Plate  LVI,  Fig.  11. 

Description. — Shell  short,  ventricose,  posteriorly  acute,  anterior  regu- 
larly rounded.  Surface  marked  with  very  regular,  concentric  folds, 
with  narrow,  sharply  incised  interspaces. 

Length,  11  mm.;  height,  5 mm. 

Occurrence. — Aquia  Formation.  2 miles  below  Potomac  Creek,  Po- 
tomac Creek,  Aquia  Creek,  Liverpool  Point,  Clifton  Beach. 

Collection. — Maryland  Geological  Survey. 

Leda  tysoni  n.  sp. 

Plate  LYII,  Figs.  4,  4a,  5. 

Desci'iption. — Shell  of  moderate  size,  thin,  not  extremely  inequilateral; 
beaks  large,  proximate;  anterior  end  produced,  uniformly  rounded;  pos- 
terior end  broad,  uniformly  rounded;  surface  marked  by  fine,  regular 
closely-set  rounded  lamellae  with  narrow  interspaces;  hinge-line  nearly 
straight  with  from  twelve  to  fifteen  teeth  on  either  side  of  a subum- 
bonal  chondrophore. 

This  species  has  some  resemblance  to  the  figures  of  Nucula  capsiopsis 
de  Gregorio.'^ 


Ann.  Geol.  et  Pal.,  vol.  ii,  p.  187,  pi.  xxii,  figs.  28,  24. 


202 


SYSTEMATIC  PALEONTOLOGY 


Length,  12  mm.;  height,  6.5  mm. 

Occurrence. — Nanjemoy  Fokmation.  Popes  Creek,  Woodstock,  1 
mile  southeast  of  Piscataway,  2J  to  3 miles  above  Popes  Creek. 

Collections. — Maryland  Geological  Survey,  Philadelphia  Academy  of 
Natural  Sciences. 

Family  NUCULIDAE. 

Genus  NUCULA  Lamarck. 

Nucula  ovula  Lea. 

Plate  LVII,  Fig.  6. 

Nucula  ovula  Lea,  1833,  Contrib.  to  GeoL,  p.  80,  pi.  iii,  fig.  59. 

Description. — Shell  ovate,  oblique,  inflated,  very  inequilateral,  trans- 
versely striate,  longitudinally  and  very  minutely  ribbed;  substance  of 
the  shell  thin;  lunule  large,  not  deeply  impressed;  beaks  pointed,  re- 
curved; anterior  series  of  teeth  short,  posterior  series  long;  fosset  nearly 
direct;  cavity  of  the  shell  deep;  margin  very  minutely  crenulate;  nacre 
pearly.”  Lea,  1833. 

Length,  11  mm.;  height,  7.5  mm. 

Occurrence. — Aquia  Foemation.  Tipper  Marlboro,  Sheckeks  Farm 
near  South  Eiver. 

Collection. — Maryland  Geological  Survey. 

Nucula  potomacensis  n.  sp. 

Plate  LVII,  Figs.  7,  7a,  8,  8a. 

Nucula  magnifica  Clark,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Nucula  magnifica  Clark,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  82. 

Not  Nucula  magnifica  Conrad. 

Description. — Shell  small,  thin,  fragile;  valves  shallow;  surface  mark- 
ed by  strong  radial  striae  which  are  stronger  toward  the  periphery,  and 
along  which  the  shell  tends  to  fracture;  margin  strongly  crenulated; 
lines  of  growth  faint  and  irregular,  other  concentric  sculpture  lacking; 
interior  with  a silvery  luster;  beaks  anteriorly  situated;  lunule  indis- 
tinct; chondrophore  narrow,  oblique;  anterior  teeth  about  fifteen,  pos- 
terior teeth  about  six. 


MARYLAND  GEOLOGICAL  SURVEY 


203 


Length,  11  mm.;  height,  8 mm. 

Occurrence. — Xanjemoy  Formation.  Woodstock,  Head  of  Xanjemoy 
Creek,  Charles  Branch  between  Eosaryville  and  Upper  Marlboro,  Popes 
Creek,  East  and  west  of  Port  Tobacco,  Tapper  Marlboro  (deep  cut  near 
Chesapeake  Beach  E.  E.  station),  miles  above  Popes  Creek. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University. 


MOLLUSCOIDEA. 

Class  BRAG  H 10  POD  A. 

Order  TELEOTREMATA. 

Family  TEREBRATELLIDAE. 

Genus  PLATIDIA  Costa. 

Platidia  marylandica  n.  sp. 

Plate  LYIII,  Figs.  1,  la,  lb,  Ic. 

Description. — Shell  small,  subcircular,  somewhat  depressed,  with  well- 
marked  lines  of  growth;  ventral  valve  with  hinge-area  prominent,  high, 
bisected  by  a large  open  foramen  and  with  a well-defined,  linear  septum 
in  the  interior;  dorsal  valve  with  large  pedicle  incision,  and  with  a short, 
high,  slightly  bifurcated  medium  septum  in  the  interior;  teeth  and 
sockets  prominent;  shell  structure  minutely  punctate. 

This  beautiful  little  brachiopod  is  not  uncommon  at  Upper  Marlboro 
where  it  is  found  associated  with  bryozoans  and  foraminifera.  There  is 
no  other  American  fossil  species  of  this  genus. 

Length,  4 mm.;  width.  4 mm. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 


204 


SYSTEMATIC  PALEONTOLOGY 


Family  TEREBRATULIDAE. 

Genus  TEREBRATULA  Llhwyd. 

Tekebratula  haelani  Morton. 

Plate  LVIII,  Figs.  2,  3,  3a. 

Terebratula  harlani  Morton,  1829,  Jour.  Acad.  Nat.  Sci.  Phila.,  vol.  vi,  p.  73,  pi. 
hi,  tigs.  1-4,  7,  8;  Amer.  Jour.  Sci.,  vol.  xvii,  p.  283;  vol.  xviii,  pi.  iii,  tig. 
16. 

Terebratula  harlani  Bao-g,  1898,  Amer.  Geol.,  vol.  xxii,  p.  370. 

Description. — Shell  large,  about  twice  as  long  as  broad,  sides  straight 
and  imperfectly  parallel;  upper  valve  plano-convex,  obscnrely  bipli- 
cated  except  near  the  margin,  which  has  three  inconsiderable  sinuses; 
loAver  valve  very  convex,  with  a longitudinal  ridge  and  slight  lateral 
depressions;  beak  incurved;  umbo  prominent.’^  Morton,  1829. 

Mr.  Schuchert  states  in  a private  communication  that  The  Tere- 
bratula  harlani  from  the  Eocene  show  a tendency  to  variation  which  if 
constant  I would  use  as  a distinguishing  character  for  the  establishing 
of  a variety.  This  tendency  is  for  the  shell  to  become  a little  wider  with 
the  loss  of  lohation.  Similar  shells  also  occur  among  the  Cretaceous 
specimens  hut  the  form  seems  to  he  rare.  If  in  the  Eocene  this  form 
is  the  prevailing  one  then  it  shows  the  line  of  variation  in  evolution. 
However,  if  you  give  these  Eocene  specimens  a varietal  name,  call  atten- 
tion to  the  fact  that  the  identification  cannot  he  made  from  single 
specimens. 

Another  slight  difference  is  the  wide  area  on  each  side  of  the  crural 
processes.  This  also  has  no  particular  value.  I should  never  have  be- 
lieved the  finding  of  Terebratula  harlani  in  Eocene  strata  had  I not 
seen  these  specimens  with  your  remarks  as  to  occurrence  and  associated 
Eocene  fossils.^’ 

Whether  the  specimens  of  Terebratula  harlani  found  associated  with 
typical  Eocene  fossils  are  to  he  regarded  as  mechanically  derived  from 
Cretaceous  deposits  or  are  really  Eocene  representatives  of  this  import- 
ant species  the  authors  have  not  been  able  to  determine.  A careful 
study  of  the  many  shells  found  does  not  afford  any  evidence  that  they 
were  transported  to  any  distance  although  in  some  instances  occurring 
well  above  the  base  of  the  Eocene.  Furthermore,  it  cannot  be  definitely 


MARYLAND  GEOLOGICAL  SURVEY 


205 


shown,  so  far  as  these  occurrences  are  concerned,  that  the  Eancocas  for- 
mation, to  which  Terehratula  liarlani  is  limited  farther  north,  really  ex- 
ists or  ever  did  exist  in  the  area  below  the  Eocene  strata.  The 
specimens  obtained,  however,  are  not  unlike  the  Cretaceous  forms. 
It  is  important  in  this  connection  that  they  have  never  been  observed 
in  the  intervening  Manasquan  and  Shark  River  formations,  both  of 
which  have  furnished  a considerable  number  of  other  species. 

The  specimens  vary  considerably  in  size,  although  the  larger  forms 
predominate.  The  largest  specimens  are  from  70  to  80  mm.  in  height 
and  10  to  50  mm.  in  width. 

Occurrence. — Aquia  Formation.  3 miles  west  of  Leeland,  Severn 
River  opposite  Annapolis. 

Collections. — Maryland  Geological  Survey,  Maryland  Academy  of 
Sciences. 


Class  BRYOZOA. 

Order  CYCLOSTOMATA. 

Family  TUBULIPORIDAE. 

Genus  DISCOSPARSA  d’Orbigny. 

Discosparsa  varians  n.  sp. 

Plate  LIX,  Fig.  3. 

Description. — Zoarium  forming  subcircular  (young)  or  irregular,  un- 
dulating expansions,  2 to  10  mm.  wide,  parasitically  attached,  or  more 
or  less  free  and  epithecated  beneath.  In  young  colonies  which  are  often 
spread  over  the  original  layer,  the  zooecial  apertures,  which  are  enclosed 
by  moderately  elevated,  ring-like  peristomes,  are,  sometimes  uniserially, 
but  never  very  regularly,  arranged  in  a radiate  manner  about  the  small, 
depressed  and  smooth  central  space.  In  older  examples,  there  are  sev- 
eral of  these  maculae,  but  the  radial  arrangement  of  the  zooecia  about 
them,  is  generally  obscure.  The  ooecia  immediately  surrounding  the 
maculae  are  often  of  larger  size  and  more  oblique  than  those  covering 
the  intermediate  spaces  where  they  are  quite  direct,  but  in  worn  ex- 
amples very  little  difference  in  size  is  noticeable.  The  interzooecial 


206 


SYSTEMATIC  PALEONTOLOGY 


spaces,  which  are  solid  and  concave  normally,  are  pitted  in  worn  speci- 
mens as  thongh  they  contained  covered  mesopores  or  vesicles.  The  nn- 
worn  covering  is  minutely  punctate,  as  are  also  the  covers  closing  some 
of  the  zooecial  apertures.  The  zooecia  form  mere  inflations  of  the  sur- 
face, usually  (perhaps  always)  over  one  of  the  maculae,  which  in  that 
case  is  slightly  raised  instead  of  depressed  and  pierced  by  somewhat 
scattered  apertures.  An  average  of  nine  zooecia  occur  in  2 mm.  Tube 
walls  as  seen  in  fractured  specimens,  thin  beneath  the  outer  crust,  min- 
utely perforated,  the  pores  arranged  in  transverse  series  with  nearly 
three  of  the  rows  in  the  space  equalling  the  width  of  a tube.  No 
diaphragms  were  observed.  Length  of  tubes,  1 mm.  or  less. 

The  Lower  Eocene  specimens  have  been  identified  with  a common 
form  in  the  washings  of  the  Lpper  Cretaceous  at  Yincentown,  N.  J.  In 
the  latter  the  arrangement  of  the  zooecia  is  usually  more  regular  and 
the  maculae  scarcely  so  noticeable  as  they  are  in  the  Upper  Marlboro 
specimens,  but  other  Yincentown  specimens  agree  very  closely  with  the 
one  illustrated  on  Plate  LIX,  Fig.  3.  The  generic  position  of  the  species 
ma)^  be  considered  a trifle  doubtful.  The  wholly  parasitic  specimens 
would  probably  be  placed  by  most  authors  under  Berenicea,  but  it  does 
not  seem  that  the  species  in  any  of  its  forms  is  ever  truly  a Berenicea. 
Besides,  these  parasitic  specimens  cannot  possibly  be  distinguished  in 
other  respects  from  the  free  laminar  and  even  discoid  specimens  here 
united  with  them.  Discosparsa  as  established  by  d’Orbigny  and  ac- 
cepted by  Pergens,  includes  discoid  or  cupuliform  zoaria,  attached  by 
the  central  portion  of  the  base  only.  The  zooecial  apertures  are  dis- 
posed irregularly  or  in  intersecting  curved  lines  about  the  center  of  the 
upper  surface.  As  these  conditions  are  fully  complied  with  by  at  least 
some  of  the  Yincentown  specimens  of  D.  varians,  it  appears  reasonable 
to  place  the  species  under  Discosparsa  rather  than  Berenicea.  There  is 
no  described  American  species  closely  resembling  D.  varians  and  none 
of  those  from  European  deposits  seem  near  enoiigh  to  require  detailed 
comparison.  The  species  is  common  in  the  Upper  Cretaceous  at  Yincen- 
town, X.  J. 

Occurrence. — Aqijia  Fokmation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 


MAKYLAXD  GEOLOGICAL  SUKVEY 


207 


Family  FASCIPORIDAE. 

Genus  FASCIPORA  d’Orbigny. 

Fascipoea  subkamosa  n.  sp. 

Plate  LIX,  Figs.  1,  2. 

Description. — Zoarium  consisting  of  small  flattened  branches,  varying 
from  snbcylindrical  to  tlabellate,  usually  about  1.5  mm.  in  thickness. 
Ends  of  branches  convex,  occupied  by  the  months  of  numerous  sub- 
equal, thin-walled,  angular  tubes,  usually  about  0.12  mm.  in  diameter. 
Sides  of  branches  with  rather  obscure  transverse  wrinkles  and  the  aper- 
tures of  the  true  or  fully-developed  zooecia.  The  latter  are  somewhat 
scattered,  though  a tendency  to  arrangement  in  series— chiefly  longitu- 
dinal— is  commonly  apparent.  The  rounded  contour  of  the  zooecial 
tube-wall  is  but  dimly  discernible  behind  the  moderately  raised  aper- 
tural  rims.  Zooecial  apertures  ovate,  about  0.14  mm.  by  0.18  mm., 
with  about  five  in  2 mm.  Interapertural  space  as  well  as  apertural 
covers,  minutely  punctate.  In  vertical  fractures  the  tubes  are  shown 
to  be  very  long  and  that  they  approach  the  surface  very  gradually. 
Ooecium  a mere  inflation  of  the  surface  through  which  one  or  more  of 
the  zooecial  tubes  pass. 

In  the  general  form  of  its  zoarium  this  species  agrees  very  well  with 
F.  pavonina  (Michelin)  d’Orbigny’s  type  of  the  genus,  but  its  zooecia 
are  much  smaller  and  not  nearly  so  prominent. 

Occurrence. — Aquia  Fokmation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Family  IDMONIIDAE. 

Genus  RETICULIPORA  d’Orbigny. 

Eeticulipoka  DlCHOTOiiA  Gabb  and  Horn. 

Plate  LIX,  Figs.  9-12. 

Reticulipora  dichoioma  Gabb  and  Horn,  1862,  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  ser., 
vol.  V,  p.  178,  pi.  xxi,  lig.  64. 

Comp.  Bicritiina  gandryana  Pergens,  1890,  Revis.  des  Bryozoaires  du  Cretace,  Bull. 
Soc.  Beige  de  Geol.,  t.  iii,  pi.  xiii,  tig.  2. 

Description. — Fragments  only  of  this  species  have  been  seen.  So  far 
as  these  admit  of  judging,  the  zoarium  is  not  reticulated  but  consists  of 


208 


SYSTEMATIC  PALEOXTOLOGY 


laterally  compressed  curved  branches,  2 to  3 mm.  wide  or  high  and 
1 mm.  or  less  thick,  throwing  oft  similar  branches  from  their  sides.  Oc- 
casionally they  appear  to  divide  dichotomonsly,  but  this  probably  is  not 
really  the  case.  The  zooecial  apertures  are  subcircular  or  oval,  0.08  to 
0.10  mm.  in  diameter,  arranged  in  more  or  less  irregular  transverse 
series,  five  or  six  in  1 mm.,  oblique,  with  the  peristome  higher  behind 
than  in  front.  Except  for  an  occasianal  large  cell  (?  zooecinm)  the 
lower  third  or  half  of  the  branches  is  without  zooecial  apertures  and  in 
the  worn  condition  may  appear  quite  solid.  When  in  a good  state  of 
preservation,  however,  this  part  of  the  surface  is  covered  by  angular 
depressions,  of  varying  sizes,  the  centers  of  the  depressions  usually  show- 
ing the  mouth  of  a small  pore.  Similar  pores  extend  upward  and  oc- 
cupy the  depressed  spaces  between  the  rows  of  zooecial  apertures.  Gon- 
ocysts  of  the  same  type  as  in  Berenicea,  Discosparsa  and  Fascipora. 
The  zooecial  tubes  pass  through  them  without  interruption,  but  the 
mesopores  do  not.  Closures  of  zooecial  tubes,  some  distance  below  the 
external  orifice,  appear  to  have  a central  perforation. 

A species  recently  described  by  Pergens  (loc.  cit)  from  the  Cretaceous 
(Senonien)  of  France,  under  the  name  of  Bicrisina  gaudryana,  is  either 
the  same  as  R.  dichotoma  or  extremely  like  it.  The  species  occurs  in 
the  Upper  Cretaceous  at  Timber  Creek  and  Yincentown,  U.  J. 

Occurrence.  Aquia  Eokmatiox.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Family  CERIOPORIDAE. 

Genus  CAVARIA  Hagenow. 

Cavaria  dumosa  n.  sp. 

Plate  LIX,  Figs.  4-8. 

Description. — Zoarium  forming  small,  bushy  masses,  consisting  of  fre- 
quently and  irregularly  dividing  and  coalescing  branches,  varying  in 
thickness  generally  from  1.5  to  2.0  mm.,  but  occasionally  reaching  3.0 
mm.  Surface  of  the  most  nearly  perfect  specimens  exhibiting  at  irreg- 
ular intervals;  small,  slightly  depressed  maculae,  smooth  or  occupied 
solely  b}'’  mesopores.  In  these  specimens  the  zooecia  are  readily  dis' 
tinguished  from  the  meso})ores  by  their  prominent  peristomes  and 


MARYLAND  GEOLOGICAL  SUEYEY 


209 


rounded  as  well  as  larger  apertures.  The  mesopores  occur  in  the 
maculae  and  in  the  depressed  spaces  between  the  zooecia,  are  something 
like  twice  as  numerous  as  the  latter,  and  have  small  though  variable 
apertures  set  in  the  bottoms  of  rounded  or  angular  depressions.  Inner 
diameter  of  zooecial  apertures  about  0.8  mm.,  with  four  in  the  space  of 
1.0  mm.  In  young  or  slightly  worn  examples  the  maculae  are  not 
readily  distinguished,  the  mesopores  relatively  larger  and  the  two  sets 
of  mouths  more  nearly  alike  than  in  the  condition  described  above. 
Gonocysts  large,  appearing  as  rounded  or  irregular  inflations  of  the 
surface  perforated  by  the  mouths  of  zooecial  tubes  which  pass  through 
them  without  interruption.  Beside  each  zooecium  is  the  orifice  of  a 
smaller  tube,  the  nature  of  which  is  not  understood.  When  the  outer 
wall  of  the  gonocyst  is  broken  away,  the  zooecial  tubes,  together  with 
the  small  tubes  accompanjdng  them,  are  turned  in  every  direction  away 
from  the  center.  Between  them  the  mouths  of  the  mesopores  are 
covered  by  a perforated  pellicle. 

The  axial  hollow  or  tube  varies  between  0.2  and  0.4  mm.  in  diameter, 
is  winkled  transversely  and  further  constricted  at  irregular  intervals. 
At  the  constrictions  a thin  curved  plate  is  often  observable,  but  that  it 
extends  completely  across  the  cavity  has  not  been  observed  and  from 
the  evidence  at  hand  it  is  at  least  doubtful  that  it  ever  does.  The  tubes, 
as  seen  in  fractures,  present  no  evidence  of  diaphragms,  but  the  con- 
necting perforations  in  the  walls  are  quite  distinct.  They  occur  mostly 
in  transverse  rows,  two  or  three  of  the  rows  in  a space  equalling  the 
width  of  a tube. 

Superficially  there  is  considerable  resemblance  between  this  species 
and  Heteropora  (Multicrescis)  parvicella  Gabb  and  Horn,  a common  fossil 
of  the  Upper  Cretaceous  deposits  at  Vincentown,  X.  J.  The  ramulets 
of  that  species,  however,  are  more  slender  and  divide  less  frequently 
while  its  zooecia  and  mesopores  appear  more  scattered.  But  the  prin- 
cipal difference  lies  in  the  central  hollow  which  is  wanting  in  Gabb  and 
Horn’s  species  and  distinguishes  Cavaria  from  Heteropora.  Of  the 
three  species  of  Cavaria  described  by  Hagenow,  only  C.  ramosa,  the 
type  of  the  genus,  is  at  all  similar.  In  this  the  axial  hollow  is  rela- 
tively larger  and  is  crossed  by  strong  transverse  partitions.  The  branches 
14 


210 


SYSTEMATIC  PALEONTOLOGY 


also  appear  to  be  smaller  and  the  apertures  of  both  zooecia  and  ineso- 
pores  smaller,  more  angular  and  less  regularly  disposed  than  in  C.  ra- 
mosa. 

Occurrence. — Aquia  Formation.  Upper  Marlboro  (in  fragments). 

Collection. — IMaryland  Geological  Survey. 

Genus  CERIOPORA  Goldfuss. 

Ceriopora  micropora  Goldfuss. 

Plate  LIX,  Figs.  13,  14. 

Ceriopora  micropora  Goldfuss,  1822,  Petr,  i,  p.  33,  pi.  x,  fig.  4c^  (not  4a-c). 

Ceriopora  micropora  Hagenow,  1851,  Die  Bryozoen  der  MaastricRter  Kreide  bildiing, 
p.  52,  pi.  V,  fig.  4. 

Description. — Among  the  Survey  material  received  for  description  is  a 
single  zoarium  agreeing  too  closely  with  C.  micropora,  as  redefined  by 
Ftagenow  and  represented  by  several  examples  in  the  authoFs  private 
collection  received  from  Dr.  Ed.  Pergens,  to  admit  of  distinguishing  it 
at  present.  The  specimen  is  depressed  globular  in  shape,  nearly  5 mm. 
in  diameter,  hollow  beneath,  and  composed  of  at  least  three  layers  of 
zooecia.  The  zooecial  apertures  are  not  very  clearly  shown  by  the  speci- 
men but  appear  to  be  a trifle  smaller,  more  unequal  and  thinner  walled 
than  in  the  Maastricht  colonies. 

Occurrence.  Xanjemoy  Formation.  2^  miles  above  Popes  Creek. 

Collectio7i. — Maryland  Geological  Survey. 

Genus  HETEROPORA  Blainville. 

HeTEROPORA  (?)  TECTA  n.  sp. 

Plate  LIX,  Figs.  15,  16. 

Description. — Zoarium  consisting  of  small,  subramose  masses  or  stems, 
2 or  3 mm.  in  thickness,  the  upper  ends  of  which  are  rounded  and  cov- 
ered uniformly  with  angular  thin-walled  tube  mouths,  about  seven  in 
1 mm.  A large  proportion  of  the  sides  of  the  specimen  figured  is  cov- 
ered with  a thin  and  minutely  punctate  pellicle,  the  tube  apertures 
covered  thereby  being  quite  obscured.  Most  of  the  apertures  showing 
through  or  piercing  the  pellicle,  are  of  rounded  form,  with  an  inside 
diameter  of  about  0.13  mm.,  and  enclosed  by  a ring-like  peristome. 


MARYLAND  GEOLOGICAL  SURVEY 


211 


Tlicse  are  regarded  as  the  true  zooecia,  the  other  tubes  being  probably 
all  of  the  nature  of  meso})ores.  In  longitudinal  sections  the  tubes  have 
thin  walls,  perforated  as  usual,  are  developed  in  any  part  of  the  axial 
region  and  approach  the  surface  in  a very  gradual  curve.  No  dia- 
pbragnis  were  observed. 

No  Ilcteropora  has  been  seen  by  the  autlior  that  resembles  this  spe- 
cies very  closely.  Indeed,  there  is  a doubt  regarding  its  belonging  to 
this  genus,  but,  after  comparing  it  with  all  the  described  genera  of  this 
section  of  the  Cyclostomata,  it  a])pears  to  agree  better  with  Heteropora 
than  with  any  of  the  other  genera. 

Occurrence. — Aquta  Formation.  Upper  ^larlboro. 

Collection. — ^faryland  Geological  Survey. 

Order  CH 1 LO STOMATA. 

Family  MEMBRANIPORIDAE. 

Genus  MEMBRANIPORA  Blainville. 

^Iembranirora  rimulata  n.  sp. 

Plate  LX,  Figs.  1,  2. 

Description. — Zoarium  adnate,  forming  a thin,  single  sheet  of  indefi- 
nite extent.  Zooecia  hexagonal  in  form,  arranged  quincuncially  with 
the  longitudinal  rows  generally  very  regular.  Apertures  occupying  the 
whole  of  the  large  opesium,  quite  regularly  ovate  in  shape.  Rim  or 
interapertural  space  narrower  than  the  oj)esia,  rounded,  sometimes  an- 
gular in  the  middle  but  oftener  with  a depressed  interzooecial  suture 
line,  marked  vdth  close  transverse  lines  or  wrinkles.  Taking  the  place 
of  an  ordinary  zooecium  isolated  cells  or,  more  commonly,  turn  or  three 
in  longitudinal  sequence,  occur  which  dilYer  from  the  rest  in  having  a 
convex  cover  with  a narrow  median  slit  and  above  the  slit  a linear  cres- 
centic impression.  These  cells  may  represent  an  unusual  type  of  ooecia 
but  more  probably  are  to  be  considered  as  a form  of  vicarious  avicularia 
or  vibracula. 

The  specimens  upon  which  the  species  is  founded  are  divisible  into 
two  varieties,  one  with  smaller  zooecia  and  opesia  and  thicker  walls 


212 


SYSTEMATIC  PALEONTOLOGY 


than  the  other.  Measuring  longitudinally  the  former  has  four  and  one- 
half  zooecia  in  2 min.,  the  other  only  three  and  a half.  Diagonally  one 
has  six,  the  other  five  in  the  same  space.  Thickness  of  zooarial  sheet 
not  exceeding  0.2  mm. 

Membranipora  perampla  Gabb  and  Horn,  which  occurs  rather  fre- 
quently in  the  Upper  Cretaceous  at  Vincentown  and  other  points  in  Hew 
Jersey,  sometimes  resembles  this  species,  but  its  zooecia  are  larger,  less 
regular,  with  irregular  spaces  often  between  the  rims  and  one  side  of 
the  latter  generally  higher  than  the  other,  while  none  of  the  covered 
cells  described  above  have  so  far  been  observed  in  it.  The  zooecia  are 
more  regularly  arranged  in  M.  rimulata  than  in  any  of  the  simple  spe- 
cies of  the  genus  known  to  the  writer,  and  this  fact,  together  with  the 
presence  of  the  peculiar  covered  cells,  is  principally  relied  upon  in  dis- 
tinguishing the  species.  Two  fragments  in  my  collection  of  Cretaceous 
bryozoa  found  at  Vincentown,  H.  J.,  and  regarded  as  Biflustra  disjuncta 
Gabb  and  Horn,  have  very  similar  covered  cells,  and,  considering  the 
variations  shown  in  my  specimens  of  this  species,  seem  to  show  a closer 
relation  to  M.  rimulata  than  to  any  other  form. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Membranipora  spiculosa  n.  sp. 

Plate  LX,  Figs.  3,  4. 

Description. — Zoarium  adnate.  Zooecia  arranged  in  quincunx  or  ir- 
regularly, oblong,  rounded  and  widest  above,  more  or  less  produced  be- 
low. Opesia  large,  normally  ovate,  the  upper  edge  nicely  rounded,  the 
lower  variable,  taking  up  about  half  of  the  length  of  the  zooecium. 
Eim  thin,  highest  above,  usually  dying  out  before  reaching  lower  ex- 
tremity of  zooecium.  Front  wall  over  lower  half  of  zooecium,  slightly 
depressed,  covered  with  small  granules  or  spines,  those  bordering  the 
edge  projecting  sharply  into  the  opesial  opening.  Ooecia  numerous, 
cucullate,  strongly  elevated,  often  with  a tubercle  or  point  forming  the 
summit.  When  a zooecium  is  without  an  ooecium  its  place  is  often  oc- 
cupied by  an  elevated  avicularium  of  moderate  size.  The  avicularia 
are  very  few  in  number  but  when  present  similar  to  those  found  in  Repto- 


MARYLAND  GEOLOGICAL  SURVEY 


213 


flustrella  lieteropora  Gabb  and  Horn.  Length  of  zooecinm  0.5  or  0.6 
innu;  width  0.25  to  0.30  inin.  The  specimen  described  shows  a single 
cell  differing  from  the  rest  in  being  closed,  a convex  cover,  at  the  upper 
extremity  of  which  a semi-circular  impression  is  distinguishable,  extend- 
ing over  the  whole. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Membranipora  angusta  n.  sp. 

Plate  LX,  Figs.  5,  6. 

Description. — Among  the  material  from  Upper  Marlboro,  there  are 
several  specimens  of  a delicate  Membranipora  that,  on  account  of  their 
imperfection  and  fragile  nature,  it  may  be  risky  to  distinguish  as  a new 
species.  However,  as  it  is  easily  recognized  and  may  prove  useful  in 
stratigrajihic  studies  the  writer  has  ventured  to  name  it  as  above.  The 
zooecia  are  shallow,  elongate,  elliptical,  hexagonal  or  rhomboidal  and 
separated  exce^it  in  young  stages  by  a thin  tuberculated  wall  common  to 
adjoining  cells  (i.  e.  there  is  usually  no  depressed  dividing  line  between 
the  zooecia).  The  inner  portion  of  the  wall  is  much  thicker  than  the 
outer,  so  that  the  mouths  of  the  connecting  pores,  of  which  there  are  at 
least  six  on  each  side  and  one  or  two  at  each  end,  are  clearly  shown  in  a 
xiew  of  the  front.  Two  specimens  have  cucullate  ooecia  as  shown  in 
Figure  5,  and  on  all  an  occasional  small  oval  or  rounded  and  slightly 
raised  avicularium  may  be  noticed.  The  zooecia  are  about  0.4  mm. 
long  and  0.2  mm.  wide.  M.  angusta  apparently  belongs  to  the  M. 
lineata  group  of  AVaters. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Genus  REPTOFLUSTRELLA  d’Orbigny. 

Eeptoflustrella  heteropora  Gabb  and  Horn. 

Plate  LX,  Figs.  8,  9. 

Jieptojlnstrella  heteropora  Gabb  and  Horn,  1862,  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd 
ser.,  vol.  V,  p.  162,  j)!.  xx,  fig.  50. 

Description. — “ Colony  encrusting  in  irregular  patches.  Cellules  in  a 
single  layer,  placed  with  but  little  regularity,  but  with  a tendency  to 


214 


SYSTEMATIC  PALEONTOLOGY 


radiating  lines;  elongate,  acuminate  anteriorly,  broadly  truncate  behind. 
Opening  snbtriangular,  with  the  sides  convex,  often  approaching  an  oval 
in  very  long  cellules.  Surface  regularly  convex,  bordered  anteriorly  and 
laterally  by  a slightly  elevated,  rounded  edge,  usually  becoming  obsolete 
as  it  approaches  the  proximal  end  of  the  cellule.  Special  pore  placed 
in  advance  of  the  opening,  small  and  round.  No  ovarian  vesicles  were 
observed.  Old  cellules  are  closed  over  by  a continuation  of  the  surface 
wall  totally  obliterating  the  aperture.  In  this  case  the  ^ special  pore  ’ 
is  also  generally  obliterated,  merely  showing  a slight  depression.^^  Gabb 
and  Horn,  1862. 

The  Eocene  specimens  are  coarser  in  appearance  than  the  Cretaceous 
form  of  the  species,  of  which  the  writer  has  a number  of  excellent 
examples.  They  differ  further  in  the  more  pronounced  character  of  the 
granulation  of  the  front  wall  and  opesial  margin,  the  Cretaceous  form 
being  almost  smooth;  in  more  frequently  assuming  a rhomboidal  form 
of  zooecium;  and  in  the  relatively  smaller  size  of  the  opesium  and  larger 
avicularia.  Cucullate  ooecia,  less  prominent  but  otherwise  similar  to 
those  of  Membranipora  spiculosa,  occur  not  infrequently  upon  the  Cre- 
taceous specimens  but  are  wanting  on  the  Eocene  material  in  hand. 
When  these  occur  they  take  the  place  of  the  avicularium  which  other- 
wise occurs  invariably  on,  or,  just  above,  the  upper  rim  of  the  zooecium. 

The  species  occurs  in  the  Cretaceous  at  Mullica  Hill,  Timber  Creek, 
and  Ahncentown,  N.  J. 

Memhra7iipora  spiculosa  is  a closely  related  species,  but  has  a more 
ovate  and  larger  opesium  and  differently  shaped  zooecia. 

Occurrence. — Aquia  Eokmation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Genus  BIFLUSTRA  d’Orbigny. 

Biflustra  torta  Gabb  and  Horn. 

Plate  LX,  Eig.  7. 

Biflustra  torta  Gabb  and  Horn,  1862,  Jour.  Acad.  Nat.  Sci.  Phila.,  2nd  ser.,  vol.  v, 
p.  152,  pi.  XX,  tig.  36. 

Description. — Colony  composed  of  very  compressed  branches,  usu- 
ally twisted,  rarely  in  the  same  plane  for  more  than  a quarter  of  an 


MAKYLAXD  GEOLOGICAL  SURVEY 


215 


inch.  Cellules  arranged  in  longitudinal  lines  and  usually  in  quincunx. 
About  six  to  ten  rows  on  each  side  of  the  branches,  although  we  have  in 
one  case  counted  twenty  just  below  a bifurcation.  Cellules  closely  jux- 
taposed; elongated  oval  anteriorly,  contracted  and  afterwards  dilated 
posteriorly,  and  straight  or  slightly  emarginate  at  the  proximal  edge. 
Opening  elongated  oval,  variable  in  form  and  size,  occasionally  sub- 
quadrate,  sometimes  slightly  narrowed  posteriorly,  either  more  or  less 
than  half  the  surface  of  the  cellule,  no  lip  or  margin,  simply  pierced  in 
the  substance  of  the  cellular  wall  and  placed  at  the  lowest  part  of  the 
surface.  Surface  smooth,  concave,  elevated  at  the  anterior  and  antero- 
lateral margins  into  a rounded  or  acute  edge,  a little  higher  than  the 
posterior  of  the  surface  of  the  adjoining  cellules.  From  this  edge  the 
surface  slopes  inwards  toward  the  mouth.  Behind  the  mouth  the  sur- 
face is  generally  marked  by  two  radiating  depressed  lines,  running  from 
the  proximal  corners  of  the  mouth  to  the  corresponding  corners  of  the 
cellule,  between  which  is  a rounded  elevation,  not  as  high,  however,  as 
the  anterior  end  of  the  preceding  cellule. 

The  accessory  cells  [vicarious  avicularia]  appear  to  be  ordinary  cellules 
undeveloped,  and  are  not  always  placed  immediately  in  advance  of  an 
ordinary  cellule.  They  are  about  two-thirds  of  the  ordinary  size,  not 
closed  above,  by  a testaceous  covering,  but  have  the  anterior  edge  very 
much  produced,  thin  and  overhanging,  and  about  as  high  as  the  length 
of  the  aperture.  We  have  noticed  but  one  broken  ovarian  vesicle,  which 
is  placed  in  advance  of  the  cellule  to  which  it  belongs,  appears  to  have 
been  semiglobular  and  overlaps  the  proximal  surface  of  the  succeeding 
cellule,  reaching  to  the  edge  of  the  aperture.^^  Gabb  and  Horn,  1862. 

Although  rather  variable  this  is  still  to  be  counted  as  an  easily  recog- 
nized species.  Ooecia  occur  but  rarel}q  only  four  or  five  specimens  out 
of  fifty  or  more  in  my  collection  having  any  at  all.  They  are  cucullate, 
often  with  a delicate  longitudinal  ridge  across  them  and  about  as  large 
as  in  Membranipora  spiculosa,  but  more  uniformly  convex.  The  species 
occurs  in  the  Upper  Cretaceous  at  Mullica  Hill,  Timber  Creek,  and 
Vincentown,  X.  J. 

Occurrence. — Aquia  Formatiox.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 


216 


SYSTEMATIC  PALEONTOLOGY 


EsCHAKA  (??)  DIGITATA  Moi’ton." 

Plate  LX,  Figs.  10,  11. 

Eschara  digitata  Morton,  1834,  Syn.  Org.  Rem.  Cretaceous  Group,  p.  79,  pi,  xiir, 
fig.  8. 

Eschara  digitata  Lonsdale,  184.5,  Quart.  Jour,  Geol.  Soc.  London,  vol.  i,  p,  73,  figs, 
c,  d,  g^  {a  and  h?)  exclus.  e and  /. 

Eschara  digitata  d’Orbigny,  1850,  Prod.  Pal.  Strat.,  vol.  ii,  p.  264. 

Eschara  digitata  Gabb  and  Horn,  1862,  Jour.  Acad.  Nat.  Sci.  Pbila.,  2nd  ser.,  vol. 
V,  p.  114. 

Description. — Zoarium  bifoliate,  branching  dichotomonsly ; branches 
flattened,  acutely  elliptical  in  cross-section,  nsnally  2.5  to  3.0  mm.  wide. 
Zooecia  hexagonal,  regularly  arranged  in  qnincnnx,  about  0.55  mm.  long 
and  0.38  wide,  bounded  by  a slightly  impressed  line;  surface  concave, 
esiiecially  toward  the  aperture  which  is  situated  usually  just  in  front  of 
the  center.  Aperture  semielliptical,  rounded  in  front,  straight  behind, 
0.10  to  0.12  mm.  wide.  Xormally  developed  and  perfect,  the  posterior 
border  of  the  aperture  is  slightly  raised  and  bears  a delicate  lunarium- 
like  curved  plate  which  extends  into  the  aperture.  Abortive  cells,  pos- 
sibly of  the  nature  of  vicarious  avicularia,  are  frequent  but  seem  to  be 
entirely  restricted  to  the  edges  of  the  zoarium  and  to  those  portions 
lying  just  beneath  the  axes  of  bifurcation.  They  are  distinguished  from 
the  other  cells  by  their  subcircular  and  usually  much  smaller  apertures. 
Ooecia  unknown.  The  species  occurs  abundantly  in  the  Upper  Creta- 
ceous at  Mullica  Hill,  Timber  Creek,  and  Vincentown,  X.  J. 

Occurrence. — Aquia  Formation.  Upper  Marlboro  (rare). 

Collection. — Maryland  Geological  Survey. 

1 Of  course  this  species  does  not  belong  to  the  genus  Eschara  as  now  understood. 
Like  Bijltistra  torta  it  belongs  near  or  to  the  genus  Onychocella  Jullian,  Avhich  is 
variously  regarded,  by  some  as  a mere  section  of  Membranipora.,  by  others  as  a distinct 
genus  or  even  as  the  type  of  a new  family,  while  Gregory  makes  it  a member  of  the 
Mxcroporidae.  At  present  I regard  Onxjchocella,  taking  such  a form  as  Memhranipora 
augulosa  Reuss,  as  a typical  species,  as  clearly  entitled  to  generic  rank  and  as  probably 
representing  a distinct  family.  It  would,  however,  to  say  the  least,  be  premature  to 
place  either  Bijlustra  torta  or  Eschara  digitata  under  Omjchocella^  since  neither  accords 
strictly  with  the  more  typical  species  of  the  proposed  genus.  When  raised  to  the 
rank  of  a family  it  is  highly  probable  that  other  generic  groups  will  be  established 
into  which  these  species  would  fall  more  naturally  than  into  Onychocella  proper. 
Careful  Mr.  Waters  has  already  instituted  a second  genus  of  the  Onychocella  type — 
Vihracella — for  Flustrellaria  trapezoidea  Reuss,  while  it  may  yet  become  desirable  to 
employ  some  of  the  names  proposed  by  d’Orbigny  for  related  types.  Under  these 
circumstances  I prefer  leaving  the  species  where  Gabb  and  Horn  placed  them. 


MAETLAXD  GEOLOGICAL  SURVEY 


21T 


Genus  LUNULITES  Lamarck. 

Luxulites  reversa  n.  sp. 

Plate  LX,  Figs.  19,  20. 

Description. — Zoariiim  flabellate  (perhaps  originally  discoid  or  de- 
pressed conical),  zooecia  snhqnadrate  or  pentagonal,  nsnally  widest  in  the 
anterior  half,  arranged  in  rather  irregular  radiating  lines,  about  six  in  2 
mm.,  with  an  impressed  line  separating  the  rows;  area  depressed,  its  sur- 
face grano-lineate.  Margin  strongly  raised,  thick,  and  straight  or 
slightly  concave  across  the  posterior  end  and  much  thinner  along  the 
sides,  the  anterior  end  appearing  to  be  overlapped  by  the  posterior  ridge 
of  the  next  succeeding  zooecinm.  Aperture  surrounded  by  a thickened 
rim,  generally  rounded  in  front  and  straighter  behind,  sometimes  sub- 
quadrate, its  anterior  border  close  to  the  prominent  end  of  the  next  cell, 
and  the  length  and  width  averaging  about  half  the  corresponding  dimen- 
sions of  the  entire  zooecinm. 

Vibracular  cells  fusiform  or  elongate  oval,  rather  large,  one,  usually 
at  each  angle  of  junction  between  four  zooecia.  A constriction  occurs 
near  the  center  of  each,  sometimes  on  one  side  only,  at  other  times  on 
both.  A narrow  area  may  surround  the  opening.  Under  surface 
marked  by  irregular  depressed  lines  radiating  from  the  narrow  lower 
extremity  of  the  zoarium.  Between  these  lines  the  surface  is  convex 
and  rather  coarsely  pitted  and  granulate. 

The  only  specimen  seen  is  too  imperfect  to  permit  a positive  declara- 
tion that  it  is  not  a mere  fragment  of  a discoid  zoarium.  Still,  the 
arrangement  of  the  depressed  lines  on  the  lower  surface  does  not  look 
right  for  a species  in  which  the  zooecia  radiate  from  a center  as  in  the 
ordinary  forms  of  Lunulites.  On  the  other  hand  this  side  looks  de- 
cidedly like  d’Orbigny^s  figure  of  his  Pavolunulites  elegans  (Pal.  Franc., 
vol.  V,  pi.  dccvi,  fig.  7),  hence  I expect  to  find  that  perfect  specimens  of 
L.  reversa  have  a fiabellate  and  not  a discoid  or  conical  form. 

Specifically,  L.  reversa  is  distinguished  from  all  species  of  Lunulites 
known  to  the  writer,  except  L.  regularis  d’Orbigny,  L.  semilunaris 
Marsson  and  L.  patelliformis  Marsson,  in  having  the  posterior  margin 
of  the  zooecinm  thicker  and  more  premoinent  than  the  anterior.  From 
the  species  mentioned  it  differs  in  the  greater  elevation  and  square  out- 


218 


SYSTEMATIC  PALEONTOLOGY 


line  of  the  raised  margin,  in  the  larger  size  and  different  form  of  the 
aperture,  and  the  grano-lineate  marking  of  the  whole  surface. 

Occurrence. — Aquia  Foemation.  2 miles  below  Potomac  Creek. 

Collection. — Mar}dand  Geological  Survey. 

'Family  CRIBRILINIDAE. 

Genus  CRIBRILINA  Hincks. 

Cribeilina  modesta  n.  sp. 

Plate  LX,  Figs.  12,  13. 

Description. — Zoarinm  forming  a delicate  parasitic  patch  upon  foreign 
bodies.  Zooecia  ovate,  not  very  regularly  arranged,  about  0.4  mm.  in 
length  and  0.28  mm.  wide,  bordered  by  a thin  rim.  Front  wall  gently 
convex,  usually  with  six  (five  to  seven)  radiating  and  transverse  furrows, 
each  with  two  or  three  pores,  on  each  side,  and  a central,  flattened,  ovate 
or  triangular  space,  including  five  or  six  similar  pores  placed  in  obscure 
transverse  furrows.  Apertures  rounded,  prominent,  oblique,  the  pos- 
terior edge  highest  and  often  thickened  in  its  central  portion.  Small 
avicularian  cells  occur  near  or  attached  to  one  part  or  another  of  the 
apertural  rim  of  most  zooecia,  generally  one  to  each,  rarely  two.  Where 
three  zooecia  join  there  is  usually  a small  open  space  (?  vibracular  cell). 
Ooecia  cucullate,  moderately  arched. 

I could  find  none  among  the  numerous  species  of  Crihrilina  and  the 
related,  if  not  congeneric,  forms  referred  to  E scliaripora,  Semiescliari- 
pora  and  Reptescliaripora  by  d’Orhigny  that  exactly  matches  the  fossil 
above  described.  It  is  distinguished  from  nearly  all  of  them  by  the 
crihrose,  central  space  on  the  front  wall,  and  the  prominent  rounded 
aperture. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Cribeilina  crassula  n.  sp. 

Plate  LX,  Fig.  14. 

Description. — Zoarium  encrusting.  Zooecia  oblong  quadrate  or  hexa- 
gonal, irregularly  arranged,  with  a heavy,  strongly  elevated  margin, 


MARYLAND  GEOLOGICAL  SURVEY^ 


219 


clithridate  in  outline.  Front  wall  with  a narrow  raised  ridge  running 
down  its  center,  and  five  or  six  transverse  and  radiating  rows  of  minute 
punctures  lying  in  furrows.  Apertures  rounded  or  subovate,  the  outline 
often  less  curved  on  the  posterior  side  than  elsewhere.  Avicularian 
cells  small,  raised,  variously  distriljuted,  sometimes  one  or  two  and  even 
three  to  a zooecium;  or  a cell  may  have  none  at  all.  Ooecia  unknown. 
Zooecia  0.5  to  0.6  mm.  in  length,  0.25  to  0.30  mm.  wide;  about  seven  in 
4 mm.  measuring  lengthwise. 

The  thick  marginal  rim  of  the  zooecia  and  the  unusual  depression  of 
the  front  wall  are  regarded  as  the  distinctive  characters.  The  latter 
feature  seems  to  occur  also  in  Escharipora  immersa  Gabb  and  Horn,  a 
species  described  but  unfortunately  not  figured  in  their  monograph,  and 
founded  on  a specimen  from  the  Cretaceous  at  Timber  Creek,  X.  J. 
Their  description  leaves  much  in  doubt,  but  as  it  is  stated  that  the 
zoarium  forms  broad,  tortuous  and  anastomosing  plates,  celluliferous 
on  both  faces,  and  that  the  zooecia  are  arranged  in  regular  quincunx, 
it  seems  highly  improbable  that  C.  crassula  can  be  the  same  species.  Of 
other  Cribrilmidae  known  to  the  writer  only  Escharipora  incrassata 
d^Orbigny,  from  the  Cretaceous  of  France,  presents  considerable  resem- 
blance. That  species,  however,  grows  into  bifoliate  expansions,  has 
larger  and  relatively  longer  zooecia  and  large  accessory  cells  ( ? vicarious 
avicularia)  not  observed  in  (7.  crassula. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Family  ESCHARIDAE. 

Genus  LEPRALIA  Johnston. 

Lepralia  subplana  n.  sp. 

Plate  LIX,  Ehgs.  17,  18. 

Description. — Zoarium,  as  seen  in  three  specimens,  forming  a hollow 
cylinder,  composed  of  numerous  la}^ers,  each  0.3  to  0.35  mm.  in  thick- 
ness, and  varying  in  diameter  according  to  the  number  of  layers  from 
7.0  to  13.0  mm.  Zooecia  not  very  regularly  arranged,  sometimes  subo- 
vate,  at  other  times  hexagonal  or  sul)quadrate,  longer  than  wide,  the 
length  averaging  about  0.45  mm.  Upper  surface  nearly  flat,  the  outline 


220 


SYSTEMATIC  PALEONTOLOGY 


of  the  zooecia^  in  aged  conditions  especially,  scarcely  distinguishable  and 
mainly  by  a double  row  of  pores  which,  as  shown  by  fractures,  are  the 
mouths  of  small  tubes  traversing  the  walls  in  a vertical  direction.  Front 
wall  slightly  convex,  perforated,  the  pores  usually  smaller  than  those 
outlining  the  zooecia,  distinctly  visible  on  the  inner  surface,  sometimes 
wanting  over  a varying  space  just  behind  the  aperture.  The  latter  is 
rounded  in  front,  nearly  straight  behind,  with  the  angles  rounded,  gen- 
erally semielliptical,  the  width  and  length  averaging,  respectively,  0.15 
and  0.13  mm.  Small,  round  or  oval  avicularia  generally  present.  Their 
position  is  variable  though  usually  close  to  the  rim  of  the  aperture. 
While  an  occasional  zooecium  may  occur,  having  no  avicularia,  as  many 
or  more  will  be  found  having  one  on  each  side  of  the  aperture.  Ooecia 
unknown. 

Fractures  dividing  the  zooecia  vertically  (see  Fig.  18)  show  that  the 
walls  (side  and  front)  are  traversed  by  minute,  wavy,  vertical  tubuli  and 
that  the  zooecial  cavities  are  connected  by  two  series  of  pores,  the  larger 
set  near  the  bottom  and  a row  of  smaller  pores  above  the  midhight. 
The  openings  of  the  larger  set  are  often  irregularly  distributed  over 
the  concave  floors  of  the  zooecia. 

A fine  specimen  from  the  Cretaceous  at  Vincentown,  N.  J.,  is  of  a 
species  closely  related  to  L.  suhplana  but  distinguished  by  several  readily 
apparent  differences.  In  it  the  young  zooecia  are  more  convex  than  in 
L.  subplana,  and  the  convex  portion  entirely  without  perforations.  With 
age,  however,  the  surface  becomes  distinctly  pitted.  The  vibracula  also 
are  more  regularly  and  numerously  developed,  most  zooecia  having  one 
on  each  side  of  the  aperture.  The  Vincentown  specimens  may  belong 
to  Gabb  and  Horn’s  Reptocdleporaria  aspera  but  certain  discrepancies 
between  it  and  their  description  and  figure  render  a positive  identifi- 
cation impossible  at  present. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Lepralia  labiosa  n.  sp. 

Plate  LX,  Figs.  15,  16. 

Description. — Zoarium  forming  thin  crusts  over  shells  and  other  for- 
eign bodies.  Zooecia  rhomboidal,  hexagonal  or  subovate,  arranged  more 


MARYLAND  GEOLOGICAL  SUEVEA" 


221 


or  less  irregularly  in  curved  series,  five  or  six  in  2 mm.  often  separated 
by  a depressed  line.  Front  wall  punctate,  slightly  convex,  fiat,  or  de- 
pressed, the  last  when  the  margin  on  one  or  both  sides  is  thickened  and 
elevated.  x\perture  subquadrate  or  semielliptical,  sometimes  contracted 
near  the  middle,  always  enclosed  by  a more  or  less  strongly  thickened 
rim.  Avicularia  occur  on  the  raised  apertural  border,  usually  one  to 
each  zooecium,  or  two,  as  shown  in  the  figures  on  Plate  LXI.  Ooecia 
unknown. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Genus  MUCRONELLA  Hincks. 

Mucronella  aspera  n.  sp. 

Plate  LX,  Figs.  17,  18. 

Description. — Zoarium  incrusting,  consisting  of  one  or  more  layers; 
surface  under  a low  power  of  magnification  presenting  a decidedly 
rough  aspect.  Zooecia  varying  from  ovate-hexagonal,  to  sub-rhomboidal, 
indistinct  externally,  arranged  more  or  less  irregularly,  though  the  rows 
are  more  regular  than  they  may  appear  at  first  sight;  about  six  in  2 
mm.  Apertures  rounded  or  subquadrate,  0.13  mm.  in  diameter,  ren- 
dered oblique  by  the  elevation  of  the  more  or  less  strongly  swollen  pos- 
terior margin  and  the  depression  of  the  anterior  part.  The  central  por- 
tion of  the  raised  lip  forms  a mucro  of  greater  or  less  thickness  and 
prominence,  the  same  hiding  a minute  central  tooth  beneath  it,  and 
forming  with  the  rest  of  the  thickened  portion  of  the  lip,  a more  or  less 
obscure  resemblance  to  the  figure  M.  Behind  the  lip  the  surface  slopes 
rapidly  and  in  the  most  nearly  perfect  example  is  granulose.  In  the 
depressed  space  in  front  of  the  aperture  there  are,  normally,  three 
small  raised  avicularia  (?  vibracula)  while  a few  larger  avicularia,  dif- 
fering further  from  the  others  in  being  divided  into  two  unequal  parts 
by  a cross-bar,  ar^  scattered  without  order  among  the  zooecia.  Ooecia 
are  not  often  seen.  When  present,  they  occupy  the  depressed  space 
in  front  of  the  aperture,  are  cucullate,  about  as  large  as  the  zooecial 
aperture,  and  usually  bear  a furrow  running  from  the  summit  to  the 
concave  edge. 


222 


SYSTEMATIC  PALEONTOLOGY" 


While  the. appearance  presented  by  the  surface  of  the  zoarinm  is  sub- 
ject to  considerable  variability^  the  essential  characters  are  nevertheless 
very  constant.  Compared  with  the  numerous  described  species  possess- 
ing a mucronate  aperture,  none  seems  to  be  nearer  than  the  form 
described  by  Gabb  and  Horn  under  the  name  Escliarifora  typica.  How- 
ever, aside  from  the  obvious  zoarial  differences  between  the  two  species, 
that  one  being  erect  and  bifoliate,  the  surface  characters  of  the  zooecia 
are  sufficiently  different  to  obviate  all  necessity  for  detailed  comparisons. 
Any  one  familiar  with  the  fossils  can  scarcely  fail  to  distinguish  them 
at  a glance.  The  species  occurs  in  the  Cretaceous  at  Yincentown,  H.  J. 

Occurrence. — A quia  Fokmation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

COELENTERATA. 

Class  ANTHOZOA. 

Order  HEXACORALLA. 

Family  TURBINOLIDAE. 

Genus  FLABELLUM  Lesson. 

Flabellum  sp. 

Plate  LXI,  Figs.  3,  3a. 

Flabellum  sp.  V"aughan,  1900,  Mon.  U.  S.  Geol.  Survey,  No.  39,  p.  66. 

Description. — Corallum  compressed  cuneiform,  attached  by  a short 
pedicel,  with  slightly  developed  marginal  wings  above  the  pedicel.  The 
dimensions  of  the  two  largest  specimens,  whose  outer  surface  is  unfortu- 
nately so  very  much  corroded  that  its  detail  is  destroyed,  are: 


1 2 

mm.  mm. 

Greater  diameter  of  calice 14  13 

Lesser  diameter  of  calice L 9 7 

Height  of  corallum 15  15 


“ Distinct  costae  correspond  to  the  larger  septa.  The  number  of  the 
septa  was  not  determined  with  certainty,  but  is  about  forty. 

This  may  be  a new  species,  but  has  a suggestive  resemblance  to  some 


MARYLAND  GEOLOGICAL  SURVEY 


223 


varieties  of  F.  cuneiforme,  and  especially  to  the  older  varieties  of  that 
species.'^  Yanghan,  1900. 

Since  the  above  was  published  Professor  Clark  has  sent  me  three  more 
specimens  of  this  same  species,  bnt  the  material  is  not  yet  sufficient  to 
determine  whether  the  species  is  new  or  only  a varietal  form  of  some 
species  of  the  genus  found  further  south.  The  best  specimen  is  rep- 
resented by  Plate  LXI,  Figs.  1,  2.  The  dimensions  of  this  specimen 
are:  greater  diameter  of  calice,  15.5  mm.;  lesser  diameter  of  calice,  8 
mm.;  height  of  corallum,  P2.5  mm.  This  specimen  is  not  so  elongate 
as  the  two  specimens  whose  measurements  are  given  above,  but  there 
is  sufficient  material  to  show  that  they  represent  only  a single  species. 
It  possesses  nineteen  large  septa  that  reach  the  columella;  in  each  of 
eighteen  of  the  loculi  between  these  large  septa  are  three  septa,  one 
longer  with  a shorter  on  each  side.  In  one  loculus  there  is  a solitary 
short  septum. 

Comparison  may  be  made  with  Flabellum  cuneiforme  var.  pacliypliyllum 
Gabb  and  Horn,  Flabellum  cuneiforme  var.  wailesi  Conrad,  and  Flabel- 
lum jolinsojii  Vaughan.  From  the  first  it  differs  by  its  epitheca  being 
not  so  dense,  and  the  corallum  is  not  so  solid,  the  corallum  is  more 
fragile;  the  second  is  coarser  and  larger;  F.  jolinsoni  is  not  so  compressed, 
the  measurements  of  its  calice  are:  greater  diameter  about  11  mm., 
lesser,  about  10  mm.  or  slightly  greater.  The  specimens  from  Virginia 
and  Maryland  are  probably  nearest  to  F.  jolmsoni.  Its  horizon  is  the 
Woods  Bluff  beds  of  Alabama. 

Occurrence. — Xan.jemoy’  Formation.  Woodstock  (three  specimens). 
Aquia  Formation.  x\quia  Creek  (six  specimens),  1 mile  southeast  of 
Piscataway  (two  specimens,  including  the  one  figured). 

Collection. — Maryland  Geological  Survey. 

Family  TURBINOLIDAE  Milne-Edwards  and  Haime. 

Genus  TURBINOLIA  Lamarck. 

Turbinolia  acuticostata  Vaughan. 

Plate  LXI,  Figs.  4,  4a,  4b. 

Turbinolia  acuticostata  Vaughan,  1895,  Johns  Hopkins  Univ,  Circ.,  vol.  xv,  p.  6. 

Turbinolia  acuticostata  Vaughan,  1896,  Bull.  No.  141,  U.  S.  Geol.  Survey,  p.  89. 

Turbinolia  acuticostata  Vaughan,  1900,  Mon.  U.  S.  Geol.  Survey,  No.  39,  p.  89,  pi. 
vi,  figs.  13-136. 


224 


SYSTEMATIC  PALEONTOLOGY 


Description. — Conical  in  shape,  as  is  nsnal  in  the  genns.  Size  small. 
Costae  tall  and  thin  with  crenate  margins.  Beginning  with  6,  6 more 
costae  are  soon  developed,  making  12,  between  which  in  the  intercostal 
furrows  are  double  rows  of  perforations.  The  12-costal  condition  exists 
for  about  1.5  mm.  from  the  base,  when  12  more  costae  are  introduced. 
The  costae  on  the  basal  portion  of  the  corallum  are  very  slightly  larger 
than  they  are  on  the  upper  portion;  they  are  not  so  prominent  on  the 
basal  portion  as  in  Turbinolia  pharetra.  In  the  extreme  upper  portion 
24  rudimentary  costae  are  introduced,  making  the  total  number  48, 
twice  as  many  costae  as  septa.  In  the  intercostal  furrows,  after  the  de- 
velopment of  the  rudimentary  costae,  there  are  only  single  rows  of  per- 
forations; during  the  24-costal  stage  there  are  double  rows  of  alternating 
perforations  in  the  intercostal  furrows.  The  septa  are  24  in  number,  in 
three  cycles.  Those  of  third  cycle  fuse,  about  half-way  between  the 
corallum  wall  and  the  columella,  by  their  margins  to  the  sides  of  those 
of  the  first  cycle.  The  septal  faces  are  beset  with  distinct,  sharp,  small 
spines.  All  of  the  septa  except  those  of  the  first  cycle  are  thin  and  weak. 
Columella  weak,  terminated  by  a small  hexagonal  star.  Height,  6.5 
mm.;  diameter  of  calice,  3 mm.’^  Vaughan,  1900. 

Since  the  original  diagnoses  of  this  species  and  T.  wautuhbeensis  ^ 
were  prepared  additional  specimens  have  come  to  notice,  making  a 
revision  of  the  critical  remarks  on  these  species  necessary.  The  speci- 
men of  T.  acuticostata  from  Popes  Creek  possesses  a weak  columella, 
with  a stellate  upper  termination.  Additional  specimens  of  T.  wautub- 
beensis  collected  by  Mr.  Frank  Burns  at  Wautuhhee,  Mississippi,  show 
that  that  species  possesses  costae  with  crenate  margins.  The  costae 
of  the  original  type  of  T.  wautubbeensis  are  probably  worn.  These  facts 
have  shown  that  these  two  species  are  so  closely  related  that  it  seemed 
that  it  might  he  necessary  to  unite  them,  however,  there  are  still 
important  differential  characters.  The  costal  crenations  of  T.  acuti- 
costata are  coarser  than  those  of  T.  wautubbeensis,  and  the  incisions 
between  the  crenations  in  the  former  species  are  deeper  than  in  the 
latter.  The  columella  in  well-preserved  specimens  of  T.  wautubbeensis 
is  stouter  than  in  T.  acuticostata,  but  there  is  not  sufficient  good  ma- 

1 Mon.  U.  S.  Geol.  Survey,  No,  39,  p.  88,  pi.  vi,  figs.  11-12, 


MAEYLAKD  GEOLOGICAL  SUKTEIT 


225 


terial  to  determine  the  value  of  this  feature.  T.  wautuhbeensis  is  the 
more  robust  species,  T.  acuiicostata  is  more  slender.  The  last  men- 
tioned difference  is  the  most  striking  one.  It  is  extremely  probable 
that  T.  wautnhbeensis  is  a direct  descendant  from  T.  acuiicostata. 

T.  yliaretra  Lea  also  possesses  a columella  with  a hexagonal  upper  ter- 
mination. It  does  not  possess  rudimentary  costae,  and  the  costae  have 
entire  edges,  hut  it  and  the  two  above  discussed  species  are  very  closely 
related  and  probably  should  he  grouped  in  a section  or  subgenus  of 
Turhinolia. 

Occurrence. — ^N'axjemoy  Formation.  Popes  Creek.  Aquia  Forma- 
tion. Potomac  Creek. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 
Family  CARYOPHYLLIDAE. 

Genus  TROCHOCYATHUS  Milne-Edwards  and  Haime. 

Trochocyathus  CLARKE  anus  Vaughau. 

Plate  LXI,  Figs.  5,  5a,  6,  7,  8. 

Paracyathufi  {?)  clarkeanus  Vaughan,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  6. 

Paracyathns  {?)  clarkeanus  Vaughan,  1896,  Bull.  No.  141,  U.  S.  Geol.  Survey,  p.  89. 

Trochocyathus  clarkeanus  Vaughan,  1900,  Mon.  U.  S.  Geol.  Survey,  No.  39,  p.  100, 

pi.  vii,  flgs.  20-23. 

Description. — ‘^‘^Corallum  conical,  usually  slightly  curved.  Cross-section 
elliptical.  Nearly  ahvays  showing  a distinct  area  of  attachment,  which 
is  variable  in  size.  Costae  not  very  prominent;  acute;  48  in  number, 

corresponding  to  all  the  cycles  of  the  septa;  nearly  equal  in  size.  In 

young  specimens  those  corresponding  to  the  last  cycle  of  septa  are 
smaller  than  those  earlier  developed.  No  epitheca  M'as  observed  and  is 
most  probably  absent.  Septa  thin,  not  exsert,  sides  granulated;  48  in 
number,  arranged  in  six  systems  of  four  cycles  each;  those  of  the  first 
three  cycles  reach  the  columella;  the  fourth  cycle  fuse  by  their  inner 
margins  to  the  sides  of  the  third  cycle.  Calicular  fossa  shallow.  Pali 
apparently  before  all  of  the  cycles  of  the  septa  except  the  last,  small 
and  thin,  and  appear  to  be  arranged  in  tivo  crowns.  Eudimentary  dis- 
sepiments apparently  present.  Columella  fascicular;  upper  surface 
papillate.”  Vaughan,  1900. 

15 


SYSTEMATIC  PALEONTOLOGY 


22() 

The  measurements  of  the  two  specimens  are: 

1 2 

mm.  mm. 

Greater  diameter  of  calice 7 7.75 

Lesser  diameter  of  calice 6 5.c 

Height  of  corallum 12.5  9.75 

The  specimens  on  which  this  species  is  founded  are  all  imperfect.  I 
could  not  obtain  accurate  details  concerning  the  characters  of  the  col- 
umella or  of  the  pali,  but  the  species  seems  to  present  all  the  essential 
characters  of  Trochocyatlius  and  is  therefore  referred  to  that  genus. 
There  is  no  other  species  of  coral  with  which  it  could  be  confused; 
therefore  critical  notes  are  unnecessary. 

Occurrence. — Aquia  Formation.  Potomac  Creek,  Aquia  Creek,  1 
mile  northeast  of  Piscataway,  Marlboro  Point. 

Collections. — Johns  Hopkins  University,  U.  S.  National  Museum, 
Maryland  Geological  Survey. 

Genus  PARACYATHUS  Milne-Edwards  and  Haime. 

Paracyathus  marylandicus  n.  sp. 

Plate  LXI,  Figs.  9,  9a,*  9b. 

Description. — Corallum  low,  subcylindrical,  attached  by  a wide  and 
somewhat  expanded  base.  Dimensions:  greater  diameter  of  calice,  5.75 
mm.;  lesser  diameter  of  calice,  5 mm.;  height  of  corallum,  5 mm.;  great- 
est width  of  base,  6.5  mm. 

Outer  surface  of  corallum  glossy,  apparently  epitheca  is  present.  Cos- 
tae corresponding  to  all  septa,  low,  alternately  larger  and  smaller  in 
size  near  the  calicnlar  margin,  but  equal  near  the  base,  densely  granu- 
lated and  slightly  crested  along  the  summit.  Granulations  also  present 
between  the  costae.  Upper  septal  margins  very  slightly  exsert.  Septa 
crowded,  thin,  in  four  complete  cycles;  the  six  primaries  slightly  the 
largest  and  somewhat  more  prominent;  the  secondaries  slightly  smaller 
than  the  primaries;  the  quaternaries  are  the  smallest  and  the  least  prom- 
inent. The  septal  faces,  beset  with  small,  low,  conical  granules.  Septal 
margins  entire,  sometimes  transversely  undulate.  Pali  present  before 
all  except  the  last  cycle  of  septa  and  arranged  with  diagrammatic  regu- 


MAEYLAXD  GEOLOGICAL  SURVEY 


227 


larity.  Those  before  the  septa  of  the  first  cycle  are  small,  and  stand 
not  very  high  above  the  papillae  of  the  columella;  those  before  the  mem- 
bers of  the  second  are  wide  and  thin;  those  before  the  members  of  the 
third  cycle  are  very  wide  and  thin,  they  extend  fnlly  one-half  the  dis- 
tance from  the  outer  limit  of  the  colnmella  to  the  wall.  The  pali  be- 
fore the  septa  of  the  second  and  third  cycles  arched  upward,  their  sides 
are  granulated  in  a measure  similar  to  the  sides  of  the  septa,  their 
margins  are  entire  • and  transversely  nndnlate.  The  calicnlar  fossa  is 
deep,  the  bottom  is  gently  concave.  The  upper  surface  of  the  colnm- 
ella consists  of  nnmerons  papillae. 

There  are  from  the  Eocene  of  the  Gulf  states  two  species  with 
which  this  species  should  be  compared.  The  first  is  Paracyathus 
granulosus  Vanghan  from  Woods  Bluff,  Alabama.  The  septa  of  the 
first  and  second  cycles  in  P.  gra^iulosus  are  much  stouter  and  have  much 
more  prominent  margins  than  in  P.  marylandicus.  The  costae  of 
P.  granulosus  are  thicker  and  are  more  prominent  than  in  P.  mary- 
landicus. The  latter  difference  will  be  made  clear  by  comparing  the 
figures  of  the  latter  species  given  here  with  the  original  figures ' of  the 
former.  The  other  is  Paracyathus  alternatus  Vaughan,  from  the  Lower 
Claiborne  of  Louisiana,  Mississippi  and  Texas.  It  exhibits  many  points 
of  difference.  Its  costae  and  septa  are  thicker  and  very  much  more 
prominent.  The  pali  are  also  different.  They  are  stouter  and  fre- 
quently are  bilobedb  P.  marylaaidicus  is  strikingly  different  from  any 
other  of  our  Eocene  species  of  Paracyathus. 

Occurrence. — Aquia  Formation.  1 mile  northeast  of  Piscataway. 

Collection. — Maryland  Geological  Survey. 

Genus  BALANOPHYLLIA  Searles-Wooci. 

Balaxopiiyllia  desmophyllum  Milne-Edwards  and  Haime. 

Plate  LXI,  Figs.  10,  11. 

Balanophrjllia  desmophyllum  Milne-Edwards  and  Ilaime,  1848,  Mon.  des  Eupsam- 
mides,  Annales  sci.  nat.,  3d  ser.,  vol,  x,  p.  86. 


1 Mon.  U.  S.  Geol.  Survey,  No.  39,  pi.  viii,  fig.  15a. 

2 Op.  sup.  cit.,  pi.  viii,  fig.  11a. 


228 


SYSTEMATIC  PALEONTOLOGY 


BalanophyUia  desmophyllum  Milue-Edwards  and  Haime,  1850,  Mou.  Brit.  Fossil 
Corals.  Palaeontogr.  Soc.,  pp.  85,  30,  pi.  vi,  figs.  1 and  \a-lc. 

BalanophyUia  desmophyllum  Milne-Edwards  and  Haime,  1857,  Hist.  Nat.  des  Coral!., 
vol.  iii,  p.  102. 

BalanophyUia  desmophyllum  Quenstedt,  1881,  Roliren-n.  Sternkorallen,  p.  1002. 
BalanophyUia  desmophyllum  Vangban,  1900,  Mon.  U.  S.  Geol.  Survey,  No.  39,  p.  164, 
pi.  xviii,  figs.  ll-13a. 


Description. — Corallum  siibflabelliform,  attached  by  a short  pedicel, 
transverse  outline  elongate  elliptical.  Calice  rather  deep.  Septa  thin, 
in  five  cycles.  The  members  of  the  first  and  second  cycles  with  promi- 
nent upper  margins.  The  margin  of  the  third  also  exsert,  but  not  to  so 
great  a degree  as  in  the  first  and  second  cycles.  The  members  of  the 
fourth  cycle  have  the  least  prominent  margins.  Those  of  the  fifth 
cycle  meet  and  unite  in  front  of  the  fourth  and  then  fuse  to  the  sides 
of  the  third.  They  are  very  perforate.  Their  surfaces  are  granulate. 
There  are  no  dissepiments.  Costae  rather  fine,  crowded  together.  Those 
corresponding  to  the  first,  second  and  third  cycles  coarser  than  those 
corresponding  to  the  fourth  and  fifth  cycles.  Those  costae  correspond- 
ing to  the  fourth  and  fifth  cycles  fine,  acute,  present  a serrate  appear- 
ance when  seen  from  the  side,  composed  of  a single  row  of  granules; 
those  corresponding  to  the  first,  second  and  third  cycles  of  septa  con- 
sist in  their  lower  portion  of  a single  row  of  granules,  but  in  their  upper 
portion  of  a double  row.  Branching  by  trifurcation.  In  old  speci- 
mens the  costae  of  the  upper  portion  are  wider  and  more  granulated. 
Occasionally  a septum  of  the  fourth  cycle  will  be  fused  distally  to  one 
of  the  second  cycle  and  a single  costa  will  correspond  to  the  two  septa. 
The  perforations  in  the  intercostal  furrows  are  very  close  together. 
Wall  rather  dense,  vesiculated.  Epitheca  rudimentary  or  absent.  There 
may  be  an  extremely  thin  pellicle  of  epitheca  just  above  the  place  of 
attachment.  Columella  very  well  developed,  spongy,  vesiculated. 


Greater  diameter  of  calice 
Lesser  diameter  of  calice  . 
Height  of  corallum 


12  3 

mm.  mm.  mnr. 

14  13  23 

8.5  8.3  16.5 

18.5  17.5  28.5 


The  siibflabellate  form  of  this  species  easily  separates  it  from  the 
other  older  Eocene  species  of  BalanopliyUia  in  the  United  States. 


MARYLAND  GEOLOGICAL  SURVEY^ 


229 


I have  compared  our  American  material  very  carefully  with  the 
descriptions  and  figures  of  B.  desmopJiyllum  given  by  Milne-Edwards 
and  Haime,  and  when  in  London,  in  January,  1898,  I had  the  oppor- 
tunity to  examine  the  types  of  the  species.  I have  been  unable  to  find 
any  character  by  which  the  American  specimens  can  be  separated  from 
those  from  Bracklesham  beds,  England.  Milne-Edwards  and  Haime 
give  an  account  of  the  affinities  of  B.  desmopliyllum  for  the  other  Euro- 
pean species  of  the  genus  in  their  Monograph  of  the  British  Fossil  Cor- 
als. Their  work  can  be  consulted  for  these  notes. 

Occurrence. — Aquia  Formation.  1 mile  southeast  of  Mason  Springs. 

Collection. — Maryland  Geological  Survey. 


Genus  EUPSAMMIA  Milne-Edwards  and  Haime. 

Eupsammia  elaborata  (Conrad). 

Plate  LXI,  Figs.  12,  13,  13a,  14,  14a. 

Turhinolia  elaborata  Conrad,  1846,  Proc.  Acad.  Nat.  Sci.  Phila. , vol.  iii,  p.  22,  pi.  i, 
fig.  30. 

Osteodes  elaborata  Conrad,  1866,  Check  List,  p.  2. 

Osteodes  elaborata  de  Gregorio,  1890,  Mon.  de  la  faune  eocenique,  de  PAla.,  p.  25. 

(.^)  Placosmilui  (Trocltosmilia)  co7inivens  De  Gregorio,  1890,  Mon.  de  la  faune 
eocenique  de  PAla.,  p.  255,  pi.  xliv,  figs.  25-28. 

Eupmramia  elaborata  Vaughan,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  6. 

Eupsammia  elaborata  Vaughan,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  90. 

Eupsammia  elaborata  Vaughan,  1900,  Mon.  U.  S.  Geol.  Survey,  No.  39,  p.  180,  pi. 
xxi,  figs.  3-7. 

Description. — The  folloiving  brief  description  is  based  on  the  original 
type  of  Conrad.  It  bears  the  label,  written  by  Conrad,  “ Osteodes 
elaborata  Con.,  Claiborne,  Ala.'’^  This  specimen  is  in  the  Academy  of 
Natural  Sciences  of  Philadelphia. 

Corallum  compressed,  conical,  straight;  cross-section  elliptical,  no  in- 
dication of  attachment.  Costae  rather  fine,  show  perforations;  branch 
by  trifurcation.  No  epitheca.  Wall  perforate,  spongy.  Septa  thin,  in 
five  cycles,  anastomosing  as  usual  in  Eupsammia.  Columella  spongy. 
Greater  diameter  of  calice,  12  mm.;  lesser  diameter  of  calice,  9 mm.; 
length  of  corallum,  13  mm. 


230 


SYSTEMATIC  PALEONTOLOGY 


Locality,  Claiborne,  Alabama/ 

The  following  description  is  based  on  material  from  G-reggs  Land- 
ing, xVlabama,  in  the  United  States  National  Mnsenm: 

The  corallnm  is  snbconical  or  subcnneiform,  the  cross-section  is  ellip- 
tical. The  base  is  -rather  obtnse,  usually  rounded;  very  frequently  on 
the  tip  is  a minute  scar,  showing  that  the  corallnm,  in  its  early  stages 
at  least,  is  attached.  The  adults  are  evidently  free,  and  the  basal  scar 
may  be  obliterated.  The  coralla  are  usually  straight,  but  sometimes  the 
apex  of  the  base  may  be  nearer  to  one  end  of  the  long  transverse  axis 
than  to  the  other.  There  is  no  epitheca.  The  costae  correspond  to  all 
septa;  they  are  equal,  fine  and  crowded;  they  are  acute,  with  beaded 
margins;  nearly  always  have  along  the  summit  a single  row  of  granules; 
extremely  rarely  the  row  may  be  double  for  a short  distance.  The.  septa 
are  thin,  weak,  arranged  in  five  complete  cycles,  six  systems,  with  the 
typical  Eupsammid  scheme  of  anastomosing.  The  granulations  on  the 
septal  faces  are  rather  low.  The  columella  is  lax,  spongy,  fairly  well 
developed. 

12  3 

mm.  mm.  . mm. 


Greater  diameter  of  calice 13  14  12 

Lesser  diameter  of  calice 10  11.5  10 

Height 17.5  18.5  14  + 


The  specimens  from  Virginia  are  usually  more  slender  than  those 
from  Alabama.  Fig.  12  represents  one  of  these  slender  specimens. 

The  folloAving  is  M.  de  Gregorio’s  original  description  of  Placosmilia 
(Trochosmilia)  connivens  de  Gregorio. 

Tr.  conoidea,  simplex,  elegans,  calice  elliptico,  paulo  excavato;  septis 
nnmerosis  in  6 cyclos  dispositis,  laminaribiLs,  tenuibis,  valde  angulosis 
spinulosisqiie,  apud  columellam  vix  incrussatis;  columella  carente  vel 
cellulosa,  ficta;  costulis  exterioribus  confertis,  miniitis,  granulosis.” 
Translation:  Tr.  conoid,  simple,  elegant;  calice  elliptical,  slightly 

excavated;  septa  numerous,  disposed  in  6 cycles,  thin,  delicate,  with 
very  sharp  minute  spines,  thickening  near  the  columella;  columella  ab- 

' Doubtful.  It  is  probable  that  Conrad  has  assigned  a wrong  locality  to  the 
specimen. 


MARYLAND  GEOLOGICAL  SURVEY 


231 


sent  or  cellular,  false;  external  costae  crowded  together,  minute,  granu- 
lar/^ 

The  description  suits  Eupsammia  elaborata  except  for  the  number  of 
cycles  of  septa,  and  the  columella  is  never  absent.  E.  elaborata  has  only 
five  cycles  of  septa.  M.  de  Gregorio's  figures  for  the  side  view  of  his  spe- 
cies, and  the  outlines  of  the  calice,  answer  for  E.  elaborata,  and  only  five 
cycles  of  septa  are  represented.  In  the  arrangement  of  the  septa,  how- 
ever, his  drawings  do  not  represent  what  is  found  in  Conrad’s  specie^. 
The  septal  diagrams  given  by  M.  de  Gregorio  for  other  species  of  corals 
that  I know  well  are  not  accurate,  so  it  is  not  improbable  that  these  like- 
wise are  not  correct  representations  of  what  is  found  in  the  specimens. 

I believe  that  M.  de  Gregorio  has  redescribed  E.  elaborata. 

Occurrence. — Aquia  Formation.  Potomac  Creek,  Aquia  Creek, 
Marlboro  Point,  Upper  Marlboro,  1 mile  southeast  of  Mason  Springs. 

Collections. — Philadelphia  Academy  of  Natural  Sciences,  Mar}dand 
Geological  Survey,  Johns  Hopkins  University. 

Eupsammia  conradi  Vaughan. 

Plate  LXI,  Figs.  15,  15a,  15b. 

TurhinoUa  pileolm  Conrad,  1843,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  i,  p.  837. 

Tiirhinolin  pileolus  Conrad,  1846,  Proc.  Acad.  Nat.  Sci.  Phila.,  vol.  iii,  p.  22,  pi.  i, 
iig.  26. 

EupHiimmia  pileolHn  Vaughan,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  6. 

Eupmmmia  {^)  pileolm  Vaughan,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  90. 

Eapmimnia  conradi  Vaughan,  1900,  Mon,  U.  S.  Geol.  Survey,  No.  30,  p.  183, 
pi.  XXI,  tigs.  10-10?). 

Not  TurhinoUa  pileolus  Eichwald,  Zool.  Spec.,  pt.  i,  1839,  p.  186,  pi.  iii,  tig.  1. 

Description. — Shape,  like  a very  short  cylinder  set  on  a hemisphere. 
The  basal  portion  is  very  slightly  conical,  rounded.  Very  faint  costae. 
Wall  thick,  vesiculate.  Septa  thick,  in  four  cycles;  those  of  the  fourth 
cycle  fuse  to  the  sides  of  the  third,  near  the  wall.  The  first  three  cycles 
reach  the  columella.  Sides  granulate;  columella  vesiculate.  Greater 
diameter,  13  mm.;  lesser  diameter,  11.3  mm.;  height,  11  mm. 

AVe  know  but  little  of  this  species;  only  one  specimen  seems  to  have 
been  found,  and  that  one  is  very  unsatisfactory.  I have  referred  it  to 
the  genus  Eupsammia  from  the  strong  resemblance  of  its  septal  arrange- 


232 


SYSTEMATIC  PALEONTOLOGY 


ment  to  that  of  young  forms  of  other  species.  There  is  a faint  scar  on 
the  hasC;,  which  may  he  due  to  attachment  in  its  early  stages.  More 
information  concerning  this  interesting  little  form  will  he  welcomed. 

Occirrrence.— Nanjemoy  Fokmation.  Pamnnkey  Eiver,  Kent  Co., 
Virginia. 

Collection. — Philadelphia  Academy  of  Natural  Sciences. 


ECHINODERMATA. 

CL.SS  ECHINOIDEA. 

Subclass  ECHINOIDEA. 

Order  SPATANGIDEA. 

Family  SPATANGIDAE. 

A few  fragments  of  the  tests  of  spatangoid  forms  have  been  obtained 
from  the  Eocene  of  the  Middle  Atlantic  Slope.  It  is  not  possible  to 
determine  their  generic  relations.  A single  fragment  is  figured  (Plate 
LXI,  Fig.  1). 

Occurrence. — Nanjemoy  Formation.  Evergreen,  Va. 

Collection. — Johns  Hopkins  University. 


Orders  DIADEMATOIDA  and  CIDAROIDA. 

Families  DIADEMATIDAE  and  CIDARIDAE. 

Numerous  spines  belonging  either  to  diadematoid  or  cidaroid  forms 
have  been  found  in  the  Eocene  deposits  of  Maryland  but  they  are  not 
sufficiently  distinctive  to  admit  of  generic  determination.  A single 
specimen  is  figured  (Plate  LXI,  Fig.  2). 

Occurrence. — Aquia  Formation.  Upper  Marlboro,  Potomac  Creek. 
Sheckels  Farm  near  South  Piver.  Severn  Eiver. 

Collections. — Johns  Hopkins  University,  Mar}dand  Geological  Survey. 


MARYLAND  GEOLOGICAL  SURVEY' 


2;3;3 


PROTOZOA. 

Class  RHIZOPODA. 

Order  FORAMINIFERA. 

Family  TEXTULARIDAE. 

Genus  TEXTULARIA  Defiance. 

Textularia  gramex  d'Orbigny. 

Plate  LXII,  Fig.  1. 

Textularia  gramen  d’Orbigny,  1846,  Foram.  Fossiles  Vienne,  p.  248,  pi,  xv,  ligs. 
4-6. 

Textularia  gramen  Brady,  1884,  CRal.  Kept.,  vol.  ix,  p.  365,  pi.  xliii,  ligs.  9,  10. 

Textularia  gramen  Bagg,  1898,  Cret.  Foram.  New  Jersey,  Bull.  88,  U.  S.  Geol.  Sur- 
vey, p.  29. 

Description. — Test  arenaceous,  rough,  stoutly  built,  laterally  com- 
pressed, margin  subangular;  normally  composed  of  five  to  seven  wide 
chambers  (in  our  Eocene  specimens  of  nine  or  ten)  in  each  series,  which 
are  but  slightly  convex;  posterior  end  neatly  rounded  and  in  general 
outline  very  similar  to  T.  hauerii,  but  differing  from  that  species  by  its 
more  angular  lateral  edges,  and  distinguished  from  T.  abbreviata,  which 
it  also  resembles,  in  being  less  short  and  thick. 

The  little  specimens  of  this  Textularia  from  the  localities  of  the 
Eocene  below  agree  well  in  general  characteristics  with  typical  forms 
except  in  the  greater  number  of  chambers.  They  are  composed  of 
finely  agglutinated  grains  well-rounded  and  smoothed  over  and  the 
shells  are  quite  compactly  built  for  this  species.  The  sutures  are 
slightly  depressed  giving  thus  some  relief  to  the  chambers,  especially 
to  the  final  ones.  This  is  a rare  form  in  the  Eocene  of  Maryland 
though  common  in  the  Pliocene  of  ATrginia.  In  present  oceans  it 
occurs  in  nearly  all  latitudes  hut  is  commonest  on  shallow  bottoms. 

Occurrence. — Aquia  E’ormation.  Upper  Marlboro,  1 mile  northeast 
of  Piscataway. 

Collections. — Maryland  Geological  Survey,  Johns  Hopkins  University. 


234 


SYSTEMATIC  PALEOXTOLOGA' 


Textulaeia  sagittula  Defrance. 

Plate  LXII,  Fig.  2. 

Textularia  sagittula  Uefrance,  1824,  Diet.  Sci.  Nat.,  vol.  xxxii,  p.  177;  1828,  vol. 
liii,  p.  344;  Atlas  Conch.,  pi.  xiii,  ttg.  5. 

Textularia  sagittula  Brady,  1884,  dial.  Kept.,  vol.  ix,  p.  361,  pi.  xlii,  figs.  17,  18. 

Textularia  sagittula  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  20. 

Description. — Test  elongated,  strongly  compressed,  with  sharp-angled 
peripheral  margin;  chambers  numerous,  about  ten  to  twelve  in  each 
series  in  typical  forms,  closely  set,  separated  by  short,  nearly  straight 
septal  lines  externally  visible;  aperture  linear. 

Specimens  of  this  form  occur  also  in  the  Cretaceous  (Rancocas)  of 
New  Jersey.  It  is  rare  in  the  Eocene  of  Maryland  as  are  all  species  of 
the  Textularia  type.  Three  specimens  have  been  recognized  from 
Upper  Marlboro.  In  present  oceans  this  is  one  of  the  most  wide-spread 
and  commonest  of  all  the  Textnlaridae  and  Brady  states  that  the  same 
is  time  among  the  fossil  Foraminifera.  This  may  be  attributed  to  the 
thick  and  solid  walls,  which,  though  not  definitely  arenaceous  are  so 
compactly  hnilt  of  opaque  material  that  they  are  more  readily  preserved 
than  more  delicate  types.  It  is  a shallow  water  species  of  temperate 
seas  hilt  is  reported  by  Professor  Brady  to  occur  in  the  North  Atlantic 
at  the  depth  of  2675  fathoms  and  at  1425  fathoms  in  the  South  Atlantic. 

It  occurs  in  the  fossil  condition  in  the  Cretaceous  formations  of  the 
north  of  Ireland  (Wright),  in  the  Cretaceous  of  New  Jersey,  the  Eocene 
of  the  London  Basin  (Jones,  Parker  and  Brady),  the  Lower  Eocene  of 
the  Thanet  beds  of  Pegwell  Bay  (Burrows),  the  Miocene  of  Austria, 
France,  and  elsewhere  (d'Orbigny,  Czjek,  etc.),  Miocene  of  Maryland 
and  Virginia  (Bagg),  the  later  Tertiaries  in  Italy  (Def ranee,  Jones  and 
Parker,  d'Orbigny),  the  Crag  of  England  (Jones,  Parker  and  Brady),  and 
the  Post-Tertiary  beds  of  Norway,  Scotland,  and  Ireland  (Sars,  Robert- 
son, Wright). 

Occurrence. — Aquia  Foemation.  Upper  Marlboro. 

Collections. — Johns  Hopkins  LTniversit}^  Maryland  Geological  Survey. 

Textulaeia  subaxgulata  d'Orbigny. 

Plate  LXII,  Fig.  3. 

Textularia  subangulata  d’Orbiguy,  1846,  Foram.  Fossiles  Yienue  p.  247,  pi.  xv, 
figs.  1-3. 


MARYLAND  GEOLOGICAL  SURVEY 


235 


Textuhiria  subangulata  Egger,  1857,  Neues  Jalirb..  fiir  Miu.  etc.,  p.  293,  pi.  xii, 
tigs.  15,  16. 

Textularia  subangulata  Bagg,  1898,  Bull.  Amer.  Pal.  No.  10,  p.  20. 

Description. — The  test  of  Textularia  subangulata  closely  resembles 
T.  granien,  but  it  is  separated  from  that  species  by  the  more  nearly 
straight  sutures^  more  angular  edges,  and  in  typical  forms  by  its  larger 
number  of  chambers.  The  one  specimen  of  this  form  from  the  Brook’s 
Estate  near  Seat  Pleasant,  while  it  may  possibly  be  considered  as  a 
variety  of  the  more  widespread  T.  gramen  differs  so  markedly  from  the 
common  form  that  it  has  been  placed  with  the  present  species. 

d’Orbigny’s  specimens  came  from  the  Miocene  of  Austria,  Egger’s 
from  the  Miocene  of  Ortenburg. 

Occurrence. — Aquia  Formation.  Brooks  Estate  near  Seat  Pleasant. 

Collection. — Johns  Hopkins  University. 

Genus  SPIROPLECTA  Ehrenberg. 

Spiroplecta  clarki  Bagg. 

Plate  LXII,  Fig.  4. 

spiroplecta  clarki  Bagg,  1895,  Johns  Hopkins  Univ.  Circ.,  vol.  xv,  p.  5. 

Spiroplecta  clarki  Bagg,  1896,  Bull.  Ill,  U.  S.  Geol.  Survey,  p.  91. 

Spiroplecta  clarki  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  20,  pi.  i,  tig.  1. 

Description. — Test  elongate,  textulariform,  finely  arenaceous,  firmly 
cemented;  compressed  strongly,  lateral  margins  sharp  and  very  slightly 
lobed;  surface  of  shell  rough,  of  a dull  gray  color;  chambers  at  first 
planospiral  then  l)iserially  arranged  with  nine  and  ten  respectively  on 
each  side;  aperture  a median  arched  opening;  length,  0.53  mm.;  breadth, 
0.20  mm. 

Previous  to  the  author's  discovery  of  the  above  Foraminifera  the 
genus  Spiroplecta  has  never  been  reported  from  the  Tertiary  formation 
so  far  as  known.  It  has,  liowever,  been  described  from  the  Cretaceous 
of  Mississippi  (Ehrenberg),  and  of  ^Minnesota  (Woodward  and  Tliomas), 
and  from  the  Gault  and  Clialk  of  England  (Parker  and  Jones).  Brady 
reports  its  occasional  presence  in  existing  oceans  confined  to  three  spe- 
cies, S.  annectens,  S.  hiformis,  and  S.  americana,  the  latter  found  living 
only  in  one  locality  oft'  Raine  Island.  Torres  Strait  at  the  depth  of  155 
fathoms. 


236 


SYSTEMATIC  PALEONTOLOGY 


Joseph  Wright  includes  the  genus  Spiroplecta  in  the  list  of  Post- 
Tertiary  Foraminifera  from  the  North  of  Ireland. 

The  two  specimens  which  the  writer  found  at  Woodstock  seem  to  he 
new  though  they  resemble  8.  biformis  of  Parker  and  Jones.  They  are 
separated  from  that  species^,  however,  by  their  sharp  angular  edges. 

The  distal  end  is  more  obtusely  rounded  than  in  Textularian  types 
and  the  chambers  are  less  regularly  developed. 

Occurrence. — Nanjemot:  Formation.  Woodstock. 

Collection. — Johns  Hopkins  University. 

Family  LAGENIDAE. 

Subfamily  NODOSARIDAE. 

Genus  NODOSARIA  Defrance. 

Nodosaeia  aefinis  (d’Orbigny). 

Plate  LXII,  Fig.  5. 

Deutalina  ajffinis  d’Orbigny,  1810,  Mem.  Soc.  Geol.  France,  vol.  iv,  p.  13,  pi.  i,  tig.  4. 

Nodosaria  ajffinis  Sherborn  and  Chapman,  1886,  Jour.  Roy.  Microsc.  Soc.,  2nd  series, 
■vol.  vi,  p.  748,  pi.  xiv,  fig.  38. 

JSfodomria  affinis  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  91. 

Nodomria  affi7iis  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  24. 

Descriptiofi. — Test  very  large,  nearly  straight,  more  tapering  than 
Nodosaria  bacillum,  and  without  having  the  primordial  chamber  larger 
than  the  succeeding  one;  proximal  end  acuminate;  chambers  numerous, 
nnconstricted  below  but  becoming  distinctly  so  above;  surface  marked 
by  about  ten  distinct  elevated  costae  as  in  N.  bacillum;  aperture  central, 
elevated  on  the  ultimate  chamber.  Length  9 mm.  or  more. 

Occurrence. — Nanjemoy  Formation.  Woodstock. 

Collection. — Johns  Hopkins  Hniversity. 

Nodosaria  bacillum  Defrance. 

Plate  LXII,  Fig.  6. 

Xodosm'ia  bacillum  Defrance,  1825,  Diet.  Sci.  Nat.,  vol.  xxxv,  p.  127;  vol.  xxxvi, 
p.  487,  Atlas  Conch.,  pi.  xiii,  fig.  4. 

Nodomria  bacillum  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  91. 

Nodomria  bacillum  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  24. 

Description. — Test  very  large,  straight  or  nearly  so,  surface  marked 
by  about  ten  very  distinct  snow-white  costae,  though  this  number  does 


MAEYLAXD  GEOLOGICAL  SGRYEY 


23T 


not  remain  constant,  some  specimens  liaying  only  eight  costae  below 
and  as  many  as  twelve  above;  primordial  chamber  bulbons,  acuminate, 
though  the  spine  is  frequently  broken;  segments  regular,  less  distinct 
below,  marked  by  straight,  transverse  septae  ; length  unknown  but  frag- 
ments of  nine  chambers  measure  5 mm. 

This  Nodosaria  has  been  described  from  a number  of  Tertiary  de- 
posits of  Europe  and  England  but  is  seldom  found  in  modern  oceans, 
though  Schlumberger  mentions  it  from  the  Gulf  of  Gascony. 

It  is,  like  all  Nodosaria,  not  at  all  common  in  the  Eocene  deposits  of 
the  Middle  Atlantic  Slope. 

Occurrence. — ^Iaxjemoy^  Formatiox.  Woodstock.  Aquia  Forma- 
Tiox.  3 miles  west  of  Leeland,  2 miles  below  Potomac  Creek,  1 mile 
southeast  of  Mason  Springs,  Upper  Marlboro. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

Nodosaria  commuxis  (d'Orbigny). 

Plate  LXII,  Fig.  7. 

Bentalma  communis  d’Orbigny,  1826,  Ann.  Sci.  Nat.,  vol.  vii,  p.  254. 

Bentalina  communis  3 OTies  and  Parker,  1860,  Quart.  Jour.  Geol.  Soc.  London,  vol. 
xvi,  pi.  xix,  tigs.  25,  26. 

Xoclosaria  communis  Brady,  1884,  Chal.  Kept.,  vol.  ix,  p.  504,  pi.  Ixii,  figs.  19-22. 

Nodosaria  cornnuinis  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  91. 

Nodosaria  communis  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  25. 

Description. — Test  elongate,  smooth,  with  depressed,  oblique  septa; 
primordial  chamber  larger  than  the  one  succeeding  and  in  some  of  our 
specimens  acuminate;  ultimate  chamber,  elongate,  tube-like;  transverse 
section  circular,  aperture  round,  smooth,  length  0.6  mm.  The  earlier 
description  of  this  species  was  based  on  a single  young  form  but  since 
this  time  a number  of  other  specimens  have  been  found  from  Upper 
Marlboro.  The  typical  forms  of  this  species  have  the  sutures  depressed 
and  the  chambers  all  oblique,  in  some  of  the  forms  remarkably  so. 

This  is  one  of  the  most  common  Nodosaria  in  both  fossil  and  recent 
state  and  has  a world-wide  distribution  to-day.  It  includes  a large 
number  of  variously  described  species  with  oblique  sutures  such  as  D. 
inornata,  and  D.  hadenensis,  dUrbigny  (Vienna  Basin  Monograph),  D. 
lerjumen  Peuss,  D.  snharcuaia  AVilliamson  and  many  others. 


238 


SYSTEMATIC  PALEONTOLOGY 


Occurrence. — Aquia  Formation.  Brooks  Estate  near  Seat  Pleasant, 
Upper  Marlboro. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

Hodosaeia  consobrina  VAR.  emaciata  (Keuss). 

Plate  LXII,  Fig.  8. 

Dentalma  coiuobrina  var.  emaciata  Reuss,  1865,  Denkschr.  d.  k,  Akad.  Wiss.  Wien, 
vol.  XXV,  p.  132,  pi.  ii,  tigs.  12,  13. 

Nodosaria  co?isobrma,  var.  emaciata  Brady,  1884,  Ckal.  Kept.,  vol.  ix,  p.  502,  pi.  Ixii, 
figs.  25,  26. 

Nodosaria  consobrina  var.  emaciata  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  25. 

Description. — Test  smooth,  elongate,  tapering  gracefully,  segments 
numerous,  short,  elongate  oval;  similar  in  outline  to  N.  consobrina  but 
more  elongated  and  slender;  septae  somewhat  depressed,  transverse. 
The  proximal  chamber  is  rounded  and  ends  in  a nipple-shaped  aperture. 

Both  N.  consobrina  and  the  variety  emaciata  are  found  living  in  the 
Xorth  Atlantic  at  depths  ranging  from  290  to  725  fathoms,  and  in  the 
South  Atlantic  at  350  fathoms;  off  the  Cape  of  Good  Hope,  150  fath- 
oms; and  in  the  South  Pacific,  129-1375  fathoms.^ 

This  species  has  a vdde  distribution  in  the  fossil  world.  It  is  found  in 
several  formations  of  the  Xew  Jersey  Cretaceous,  according  to  Wright 
it  occurs  in  the  Chalk  of  Ireland,  Jones  and  Parker  report  it  in  the 
London  Clay,  Eeuss,  Bornemann,  etc.,  record  it  in  the  Septaria  Clays  of 
Germany,  the  Miocene  of  Austria  (d’Orbigny),  the  later  Tertiaries  of 
Italy  (Costa),  the  Post-Tertiary  of  Norway  (Crosskey  and  Eobertson), 
the  Island  of  Ischia  (Broeck),  and  in  Scotland  (Eobertson). 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Johns  Hopkins  University. 

Nodosaeia  sandbergeri  (Eeuss). 

Plate  LXII,  Fig.  9. 

Dentalina  sandbergeri  Reuss,  1856,  Sitzungsb.  k.  Akad.  Wiss.  Wien,  vol.  xviii,  p. 
224,  pi.  i,  tig.  5. 

Description. — Test  stoutly  built,  composed  of  from  four  to  eight  cham- 
bers which  are  constricted  at  the  sutures;  primordial  chamber  larger 


1 Brady,  Cbal.  Rept.,  p.  502. 


MARYLAND  GEOLOGICAL  SURVEY 


239 


than  the  one  succeeding,  nltiinate  chamber  largest;  chambers  more  con- 
stricted towards  the  oral  end  and  none  of  them  quite  so  strongly  dis- 
tinct as  in  Eenss’  figure.  Surface  of  shell  strongly  costate  but  differing 
from  Eeuss’  specimens  in  that  most  of  our  forms  have  no  costae  upon 
the  final  segment,  though  this  feature  is  not  constant  enough  to  make 
a new  variety.  The  aperture  is  situated  upon  one  side  as  in  Marginu- 
lina  types. 

Eeuss’  specimens  were  from  the  Tertiary  deposits  of  Germany. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

XoDOSARiA  OBLiQUA  (Linue). 

Plate  LXII,  Fig.  10. 

Nautilus  obliqnus  Linne,  1767,  Syst.  Nat.,  12th  Edit.,  p.  1168,  No.  281;  1788,  Syst. 

Nat.,  13th  Edit.  (Gmelin’s),  p.  3372,  No.  14. 

Nodosaria  obliqua  Brady,  1884,  Chal.  Kept.,  vol.  ix,  p.  1.513,  pi.  Ixiv,  tigs.  20-22. 

Description. — Test  variable  in  size,  sometimes  very  large,  elongate, 
tapering,  arcuate;  septal  lines  depressed,  surface  costate,  costae  varying 
in  size  and  number  in  different  specimens;  chambers  numerous,  ventri- 
cose,  distinct;  aperture  central,  radiate. 

According  to  Professor  Brady  this  species  is  found  in  every  sea  and 
at  all  depths  from  the  laminarian  zone  down  to  1500  or  2000  fathoms. 

It  occurs  frequently  in  the  fossil  state:  Cretaceous  of  Sweden  (Nillson), 
Cretaceous  of  Mecklenburg,  and  elsewhere  (Eeuss),  Cretaceous  of  New 
Jersey  (Bagg),  Lower  Eocene,  Thanet  Beds,  Pegwell  Bay  (Burrows), 
Tertiary  of  Germany  (Eeuss,  etc.).  Tertiary  of  Italy  (Costa).  !Many 
other  references  could  easily  be  given  though  these  are  sufficient  to  show 
its  wide  distribution. 

These  forms  are  so  large  and  long  that  one  can  find  no  perfect  s])cci- 
mens  as  they  are  easily  broken  in  collecting  and  washing  the  marl.  The 
Cretaceous  forms  from  Xew  Jersey,  however,  are  frequently  perfect  and 
well  preserved. 

Occurrence. — Aquia  Formation.  Upper  Marlboro  (fragments  only). 

Collection. — Maryland  Geological  Survey. 


340 


SYSTEMATIC  PALEOXTOLOGA" 


Genus  VAGINULINA  Lamarck. 

Vagixulixa  legumex  (Linne). 

Plate  LXIII,  Fig.  1. 

JSFantilaa  legumen  Linne,  1758,  Syst.  Nat.,  10th  Edit.,  p.  711,  No.  248;  12tli  Edit., 
1767,  p.  1164,  No.  288. 

Vaginnlina  legumen  Brady,  1884,  Chal.  Kept.,  vol.  ix,  p.  530,  pi.  Ixvi,  figs.  13-15. 

Vagimilma  leg\mien  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  26. 

Vaginnlina  legumen  Bagg,  1898,  Cret.  Foram.  New  Jersey,  Bull.  88,  U.  S.  Geol.  Sur- 
vey, p.  52,  pi.  iv,  fig.  4. 

Description. — Test  nearly  straight,  pod-like,  compressed,  smooth,  con- 
sisting of  only  six  chambers;  septa  limbate,  parallel,  oblique,  less  dis- 
tinct towards  the  distal  end;  ultimate  chamber  slightly  prolonged  at  the 
anterior  end;  aperture  radiate;  length,  0.80  mm. 

The  genus  Vaginnlina  is  closely  related  to  the  ensiform  varieties  of 
Crist ellariae  and  to  the  less  flattened  form  Marginulina,  and  from  the 
curved  forms  of  Nodosaria  from  which  it  is  separated  by  its  broader 
outline  and  marginal  aperture. 

Brady  states  that  it  is  widely  distributed  over  present  oceans  and  that 
the  genus  reaches  its  greatest  abundance  in  the  North  Atlantic.  The 
species  V.  legumen  is  found  at  various  depths  down  to  2000  fathoms 
hut  it  is  commonest  in  shallow  waters. 

Tate  and  Blake  record  this  form  from  the  Yorkshire  Lias,  Jones  and 
Parker  include  it  in  the  forms  from  the  Upper  Trias  (?)  of  Chellaston, 
near  Derby;  Chapman  records  its  occurrence  from  the  Gault  of  Folke- 
stone; Burrows,  Sherhorn  and  Bailey  record  it  from  the  Bed  Chalk  of 
Yorkshire,  etc.,  and  many  other  localities  are  elsewhere  given. 

Occurrence. — Aquia  Fokmation.  Brooks  Estate  near  Seat  Pleasant. 

Collection. — Johns  Hopkins  University.  * 

Genus  MARGINULINA  d’Orbigny. 

Maeginulina  costata  (Batsch). 

Plate  LXIII,  Figs.  2,  3. 

JVautilufi  {Orthoceras)  costatus  Batsch,  1791,  Conchyl.  des  Seesaudes,  p.  3,  pi.  i,  figs 
1 a-g. 

Marginulina  costata  Brady,  1884,  Chal.  Kept.,  vol.  ix,  p.  528,  pi.  Ixv,  figs.  10-13. 

Description. — Test  rather  stoutly  built,  irregularly  costate  and  costae 
curving  about  the  distal  end;  compressed  hut  not  strongly  so;  consist- 


MARYLAND  GEOLOGICAL  SURVEY’ 


241 


ing  of  six  chambers,  largest  and  most  distinct  at  oral  end,  bluntly  acu- 
minate, aperture  on  incurved  side  of  final  chamber. 

Brady  says  of  this  form,  Individual  specimens  vary  a good  deal  in 
contour,  and  also  as  to  the  number  and  degree  of  development  of  the 
superficial  ribs;  but  the  stout  proportions  of  the  shell,  its  subcylindrical 
form,  and  comparatively  slight  curvature,  the  inflated  character  of  the 
later  chambers,  and  the  marginal  aperture,  are  generally  sufficient  to 
distinguish  it  from  costate  varieties  of  Vaginulina  and  CristeJlaria. 
The  test  is  usually  more  or  less  compressed  just  at  the  commencement, 
and  occasionally  presents  a sharp  or  even  subcarinate  edge  at  the  aboral 
end,  but  more  frequently  the  margin  is  rounded  from  the  beginning.” 

It  is  found  in  many  parts  of  the  North  Atlantic  at  depths  ranging 
from  370  to  1240  fathoms,  from  the  South  Atlantic  at  still  greater 
depths,  from  the  Mediterranean,  and  from  the  Adriatic.  Save  a few 
specimens  found  at  150  fathoms  off  the  coast  of  New  Zealand,  it  has  not 
been  observed  in  any  portion  of  the  Pacific  ocean,  in  the  Southern 
ocean  or  the  Bed  Sea. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Genus  CRISTELLARIA  Lamarck. 

Cristellaria  GIBB  a dUrbigny. 

Plate  LXIII,  Fig.  4. 

Cristellaria  fjihha  d’Orbigny,  1839,  Foram.  Cuba,  p.  63,  pi.  vii,  ligs.  20,  21. 

Cristellaria  excisa  Bornemann,  1855,  Zeitschr.  d.  deutsch.  geol.  Gesell.,  vol.  vii, 
p.  328,  pi.  xiii,  figs.  19,  20. 

Cristellaria  palchella  Reuss,  1862,  Sitzungsb.  d.  k.  Akad.  Wiss.  AVien,  vol.  xlvi, 
p.  71,  pi.  viii,  fig.  1. 

liohulina  concinna  Reuss,  1863,  Sitzungsb.  d.  k.  Akad.  Wiss.  Wien,  vol.  xlviii,  p.  52, 
pi.  V,  fig.  58. 

Cristellaria  (fibha  Bagg,  1898,  Cret.  Foram.  New  .Jersey,  Bull.  88,  U.  S.  Geol.  Survey, 
p.  56. 

Descriptim. — Test  oblong,  biconvex,  smooth,  subcarinate,  narrow; 
chambers  few  (seven  or  eight),  slightly  arcuate,  separated  by  distinct 
septa;  aperture  marginate.  Length  (Cretaceous),  1.3  mm.;  breadth,  0.87 
mm.  The  septal  face  is  rather  sharply  cut  off  from  the  whole  surface 

and  this  feature  separates  it  from  Cristellaria  acutauricularis  which  it 
16 


242 


SYSTEMATIC  PALEONTOLOGY 


closely  resembles.  Our  Eocene  forms  have  more  chambers  than  the 
Cretaceous  specimens  of  New  Jersey  which  show  nine.  The  mouth 
opening  is  also  more  prolonged  and  the  sutures  somewhat  depressed  be- 
tween the  chambers. 

This  species  is  found  in  many  places  in  the  Cretaceous  of  New  Jersey, 
Eancocas  (Bagg),  Septaria  Clays  near  Berlin  (Bornemann),  North  Ger- 
man Hils  and  Gault  (Keuss),  and  elsewhere. 

We  must  regard  the  species  as  an  intermediate  variety  between  the 
elongate  compressed  Cristellaria  crepidula,  and  the  symmetrical  lenticu- 
lar Cristellaria  rotulata.  The  form  occurs  in  the  North  Atlantic  and  in 
the  South  Pacific  at  depths  of  less  than  500  fathoms  (Brady). 

Occurrence. — Aquia  Fokmation.  1 mile  northeast  of  Piscataway, 
Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Ckistellakia  eotulata  (Lamarck). 

Plate  LXIII,  Fig.  5. 

Lenticnlites  rotulata  Lamarck,  1801,  Annales  du  Museum,  vol.  v,  p.  188,  No.  3. — 
Tableau  Eucycl.  et  Meth.,  pi.  cccclxvi,  tig.  5. 

Cristellaria  rotulata  d’Orbigny,  1810,  Mem.  Soc.  geol.  France,  vol.  iv,  p.  26,  pi.  ii, 
tigs.  L5-18. 

Cristellaria  rotulata  Parker  and  Jones,  186.5,  Phil.  Trans.,  vol.  civ,  p.  345,  pi.  xiii, 
tig.  19. 

Description. — Test  involute,  biconvex,  smooth;  peripheral  margin 
sharp,  non-carinate;  chambers  numerous,  eight  or  nine  in  final  convolu- 
tion; septa  gracefully  curved,  visible  externally  as  fine  lines;  aperture 
elliptical  radiate.  Diameter,  1-2  mm. 

While  the  above  species  is  abundant  in  the  Cretaceous  of  New  Jersey 
and  in  the  Eancocas  reaching  a large  size  for  this  type,  it  and  all  other 
Cristellariae  are  exceedingly  scarce  in  the  overlying  Eocene.  The  type 
secured  from  Mason  Springs  is  very  large  and  thick-shelled.  Since 
such  a form  would  be  readily  preserved  it  is  difficult  to  account  for  the 
lack  of  the  species  elsewhere  while  so  many  much  more  delicate  Foram- 
inifera  abound. 

It  is  doubtful  if  any  Foraminifera  is  more  widely  distributed  or  more 
abundant  either  living  or  in  fossil  state  than  Cristellaria  rotulata. 


MAEYLAXD  GEOLOGICAL  SUE  VEIT 


243 


Brady  records  its  presence  in  Arctic  waters  and  as  far  south  as  Terra 
del  Fnego  and  at  the  same  time  it  occurs  at  all  possible  depths  down  to 
2200  fathoms.  So  in  the  fossil  world  it  is  equally  widely  distributed. 
Jones  and  Parker  record  it  in  the  Upper  Trias  of  Derbyshire;  Brady  and 
Blake  have  identified  it  in  every  division  of  the  Lias  of  England.  It  is 
frequently  reported  in  the  Cretaceous  of  England  (Sherhorn,  Chapman, 
IVnght,  Sowerhy,  etc.).  It  is  abundant  in  every  division  of  the  Tertiary 
and  has  been  frequently  recorded. 

Occurrence. — xIquia  Eoematiox.  Upper  Marlboro,  1 mile  southeast 
of  Mason  Springs. 

Collection. — Maryland  Geological  Survey. 

Ceistellaeia  eadiata  (Bornemann). 

Plate  LXIII,  Fig.  6. 

Sobulina  radiata  Bornemann,  185.5,  Zeitschr.  d.  deutscli.  geol.  Gesell.,  vol.  vii, 
p.  834,  p].  XV,  fig.  1. 

Cristellaria  radiata  Bagg,  1896,  Bull.  141,  U.  S.  Geol,  Survey,  p.  91. 

GrUtellaria  radiata  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  29,  pi.  i,  fig.  3. 

Description. — Test  nearly  circular,  moderately  compressed,  with  cir- 
cular raised  umbilicus;  final  convolution  showing  ten  strongly  curved, 
even  chambers,  marked  externally  by  raised  white  septal  lines  which 
become  less  distinct  toward  the  peripheral  margin;  keel  quite  definite 
and  of  the  same  snow-white  character  and  color  as  the  raised  septa,  while 
the  chambers  are  darker  in  color  and  are  strongly  contrasted  from  the 
rest  of  the  shell.  The  surface  is  smooth  and  glistening;  the  aperture 
radiate;  diameter,  1.26  mm. 

Bornemann’s  specimens  of  Cristellaria  radiata  were  from  the  Oligo- 
cene  (Septarienthon)  of  Germany.  This  form  resembles  Cristellaria 
rotulata  but  has  the  umbilicus  raised,  and  the  septa  are  also  raised  as 
they  are  not  in  Cristellaria  rotulata.  The  keel  is  definite  hut  not  pro- 
duced into  a flange  as  in  Cristellaria  cultrata  which  form  it  closely  re- 
sembles. 

Occurrence. — Xaxjemoy  Foematiox,  Woodstock. 

Collection. — Johns  Hopkins  University. 


244 


SYSTEMATIC  PALEONTOLOGY 


Genus  POLYMORPHINA  d’Orbigny. 

POLYMORPHINA  AUSTRIACA  (d'Orbigliy). 

Plate  LXIII,  Fig.  7. 

GutUilina  austriaca  d’Orbigny,  1846,  Foram.  Fossiles  Vienne,  p.  223,  pi.  xii,  ligs. 
23-25. 

Polymorphina  austriaca  Sell  wager,  1877,  Boll.  R.  Com.  geol.  Ital.,  vol.  viii,  p.  25, 
pi.  xxxi. 

Polymorphina  austriaca  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  91. 

Polymorphina  austriaca  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  28. 

Description. — Test  oviform,  smooth,  moderately  compressed,  acum- 
inate anteriorly;  consisting  of  four  chambers  which  are  oblong,  oblique, 
and  somewhat  convex;  separated  by  fairly  deep  sutures;  aperture  mam- 
millate. 

d^Orbigny  considers  that  Guttulina  nitida  is  closely  related  to  this 
species  but  states  that  it  differs  from  it  in  its  more  elevated  chambers. 
Our  specimens  are  slightly  more  acuminate  posteriorly  than  in  d’Or- 
bigny’s  figure.  Professor  Brady  lists  this  form  among  the  synonyms  of 
Polymorphina  prohlema  but  d'Orbigny  has  shown  that  it  differs  from  the 
latter  by  its  more  convex  chambers  and  more  gibbous  form  as  a whole. 
Since  the  specific  variations  among  the  PolymorpJiinae  are  necessarily 
limited  there  is  a possible  danger  of  including  too  many  variations  under 
one  species  and  it  is  preferable,  therefore,  to  keep  the  species  distinct 
as  d^Orbigny  has  done. 

d'Orbigny^s  specimens  were  from  the  Miocene  of  Nussdorf,  Baden. 
It  is  not  a common  fossil  form  but  Terquem  has  identified  it  among 
the  Eocene  Foraminifera  of  the  Paris  Basin. 

Occurrence. — Xanjemoy  Formation.  Woodstock. 

Collection. — Johns  Hopkins  University. 

Polymorphina  communis  (d’Orbigny). 

Plate  LXIII,  Figs.  8,  9. 

Guttulina  communis  d’Orbigny,  1826,  Ann.  Sci.  Nat.,  vol.  vii,  p.  266,  No.  15,  pi.  xii, 
ligs.  1-4.  Modele,  No.  62. 

Polymorphina  communis  Brady,  1884,  Chal.  Kept.,  vol.  ix,  p.  568,  pi.  Ixxii,  flg.  19. 

Polymorphina  comnmnis  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  92. 

Polymorphina  communis  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  29. 

Description. — Test  irregular,  ovoidal,  or  egg-shaped;  consisting  of  four 
or  five  distinct  chambers;  anterior  end  extremely  acute,  posterior  obtuse; 


MARYLAND  GEOLOGICAL  SURVEY 


245 


chambers  inflated,  elliptical,  embracing;  surface  smooth  with  definite 
septal  depressions;  aperture  mammillate;  diameter,  0.35  mm. 

This  species  occurs  abundantly  in  the  New  Jersey  Cretaceous  but  the 
forms  are  much  larger  than  in  the  Eocene  of  Maryland.  The  species 
also  occurs  in  the  Pamunkey  formation  of  Virginia  on  the  Pamunkey 
River. 

This  form  is  recorded  from  the  Lower  Lias  (Blake);  Septaria  Clays  of 
Germany  (Reuss);  Gault  of  Folkestone  (Chapman);  Lower  Eocene  of 
Pegwell  Bay  (Burrows);  Red  Chalk  of  Yorkshire,  etc.  (Burrows,  Sher- 
born  and  Bailey);  and  many  other  references. 

Polymorpliina  communis  is  closely  related  to  Pohjmorpliina  proUema^ 
and  Professor  Brady  thinks  that  they  should  be  united  under  one  name 
of  P.  proUema  and  the  name  communis  be  allowed  to  drop.  In  the 
original  models  described  by  d’Orbigny  (Nos.  61  and  62),  the  forms 
portrayed  represent  clearly  distinct  species,  the  first  P.  proUema  shows 
about  seven  definite  segments  which  are  much  inflated  and  with  deep 
sutures  while  P.  communis  presents  about  four  or  five  segments  with 
less  excavated  sutures. 

In  d^Orbigny’s  great  monograph  on  the  Vienna  Basin,  both  forms  are 
included  and  the  rather  unimportant  distinctions  here  seem  to  be  that 
P.  communis  is  of  smaller  size,  the  superior  end  acuminate  and  the  su- 
tures are  complanate  while  P.  proUema  shows  an  obtuse  anterior,  exca- 
vated sutures,  larger  size  and  more  inflated  chambers. 

Reuss  considered  in  his  notes  on  Herr  von  SchlichPs  Septaria-clay 
Eoraminifera  that  P.  communis  is  a variety  of  P.  proUema  and  his  con- 
clusion may  be  accepted  ultimately,  though  for  the  present,  it  seems 
better  to  keep  them  distinct. 

Both  forms  have  a wide  distribution  tbroughout  all  oceans  but  are 
apparently  limited  to  a depth  of  less  than  155  fathoms  and  so  are  shal- 
low water  forms.  It  is  also  interesting  to  note  that  in  the  fossil  world 
they  frequently  occur  side  by  side  and  are  variously  described  from  the 
same  localities. 

The  genus  Polymorpliina  is  represented  by  a good  many  forms  of 
Eoraminifera  as  compared  with  other  types  but  they  never  become 
abundant  as  do  some  of  the  involute  genera. 


246 


SYSTEMATIC  PALEONTOLOGY 


Occurrence. — N'anjemoy  Formation.  Woodstock.  Aquia  Forma- 
tion. Upper  Marlboro. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

PoLYMORPHiNA  COMPRESSA  d’Orbigny. 

Plate  LXIII,  Fig.  10. 

Polyrnorphma  compressa  d’Orbiguy,  IS46,  Foram.  Fossiles  Vienne,  p.  253,  pi.  xii, 
figs.  32-34. 

Polymorpldna  compressa  Brady,  Parker  and  Jones,  1870,  Trans.  Linn.  Soc.  London, 
vol.  xxvii,  p.  227,  pi.  xl,  tig.  12,  a-f. 

Polyrnorphina  compressa  Bagg,  1890,  Bull.  141,  U.  S.  Geol.  Survey,  p.  92. 

Polyrnorphma  compressa  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  29,  pi.  iii.  ftg.  1. 

Description. — The  shell  or  test  of  Polyrnorphina  compressa  is  oblong, 
flatly  compressed,  inequilateral,  with  numerous  fusiform  chambers  ar- 
ranged in  a double  series.  Phiese  are  somewhat  inflated  and  the  sutures 
depressed.  The  surface  of  the  shell  is  sometimes  beautifully  striated 
longitudinally,  at  others  smooth  or  faintly  striated.  The  aperture  is 
variable,  sometimes  labyrinthic  or  porous  but  usually  simple,  circular 
and  coronate.  Its  length  is  very  variable,  in  our  specimens  from  0.82 
to  1.3  mm.,  with  a breadth  of  0.43  mm. 

This  species  is  very  common  in  the  Miocene  of  Maryland  at  Plum 
Point,  Jones  IVharf,  etc.,  and  also  in  the  Miocene  of  Virginia.  It  is, 
however,  not  abundant  in  the  Eocene.  It  has  been  identified  from  a 
well-boring  in  Norfolk,  Va.,  at  a depth  of  685  feet.  Professor  Brady 
compares  this  form  with  its  relatives  as  follows: 

In  general  terms  Polyniorpliina  compressa  may  be  said  to  include  the 
less  regularly  Textulariform  varieties  of  the  genus,  its  nearest  allies 
being  Polyrnorphina  complanata  d’Orbigny;  Polyrnorphina  frondiformis 
S.  V.  Wood;  and  Polymorphina  cylindroides  Roemer.  Of  these  the  first 
is  distinguished  by  an  exceedingly  regular  and  equilateral  Textularia- 
like  disposition  of  the  segments,  and  Polymorphina  frondiformis  by  its 
even  larger  dimensions  and  its  surface-ornament  of  interrupted  costae 
or  tubercles;  whilst  Polymorphina  cylindroides  has  a long  tapering  test, 
less  compressed  than  that  of  the  present  species  and  composed  of  a 
small  number  of  nearly  erect  segments.  , 


MARYLAND  GEOLOGICAL  SURYEA' 


247 


''  Pol iimorphina  compressa  is  a cosmopolitan  form,  especially  common 
in  temperate  latitudes.  . . . It  is  abundant  in  the  temperate  portion  of 
the  Xorth  Atlantic,  j)referring  shallow-water  margins,  hut  extending 
sometimes  to  a depth  of  400  to  600  fathoms.  In  the  tropical  South  At- 
lantic-and  in  the  Xorth  and  South  Pacific  it  is  less  frequent. 

It  has  been  recognized  as  a fossil  in  the  lower  and  middle  Lias  of  the 
west  and  north  of  England  (Brady,  Blake);  in  the  lower  Oolite,  the 
L^pper  Oxford  Cia}',  and  the  Kimmeridge  Clay  of  England  (Parker  and 
Jones),  and  in  the  Cretaceous  system  of  England,  France,  Germany,  and 
Xorth  America,  and  generally  in  the  Tertiary  and  Post-Tertiary  forma- 
tions of  Europe.” 

Occurrence. — Xaxjemoy  Formation.  Woodstock,  Well  at  Chesapeake 
Beach  at  90-92  feet. 

Collections. — Johns  Hopkins  Hniversity,  Maryland  Geological  Survey. 

PoLiTMORPHiNA  ELEGANTissiMA  Parker  and  Jones. 

Plate  LXIII,  Eig.  11. 

rohjiiiorpJnnn  elegnntissima  Parker  aud  Jones,  1865,  Phil.  Trans.,  vol.  civ,  p.  438, 
table  10. 

Pohjmorphina  ehfpmtinsiina  Brady,  Parker  and  Jones,  1870,  Trans.  Linn.  Soc.  Lon- 
don, vol.  xxvii,  p.  231,  pi.  xl,  tig.  15,  a-c. 

Pohjmorphina  elega)itinsima  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  92. 

Pohjmorphina  elegantissima  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  30. 

Description. — Test  ovoidal,  anterior  end  acute,  posterior  ol)tusely 
rounded;  chambers  four  or  five,  elongate,  arranged  in  an  inequilateral 
biserial  manner  and  overlapping  in  such  a way  that  while  one  side  re- 
mains nearly  flat  the  opposite  is  more  or  less  irregularly  vaulted  and 
shows  all  the  chambers  in  parallel  arrangement;  final  segment  broad 
below,  embracing,  and  bearing  the  mammillate  aperture  upon  the  an- 
terior end.  Shell  surface  smooth,  finely  perforate;  length,  0.60  mm.; 
breadth,  0.40  mm. 

Professor  Brady  places  under  this  species  the  form  P.  problema  var. 
delfoidea  Peiis.s,  and  P.  anceps  Penss. 

Occw/'/T/ice.— Xanjemoy  Formation.  Woodstock. 

Collection. — Johns  Hopkins  University. 


248 


SYSTEMATIC  PALEONTOLOGY 


POLYMORPHINA  GIBB  A (POrbignj). 

Plate  LXIII,  Fig.  12. 

Glohnlina  gihha  d’Orbigny,  1846,  Foram.  Fossiles  Vienne,  p.  227,  pi.  xiii,  figs.  13,  14. 

PolyrnorpJdna  gihha  Brady,  1884,  Chal.  Kept.,  vol.  ix,  p.  561,  pi.  Ixxi,  fig.  12. 

Polymorphina  gihha  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  92. 

Polymorphma  gihha  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  80. 

Description. — Test  siibglobiilar,  apex  slightly  produced;  base  obtusely 
rounded;  consisting  of  from  two  to  four  chambers  compactly  joined  and 
overlapping.  The  surface  is  smooth  and  unmarked  by  septal  constric- 
tions. Septa  visible  as  delicate,  oblique  lines;  transverse  section  nearly 
circular;  aperture  mammillate;  length  of  our  specimens,  0.35  mm.; 
breadth,  0.30  mm. 

This  is  not  a common  species  in  the  Eocene  but  the  specimens  are 
very  similar  to  those  from  the  Navesink  formation  (Lower  Marl  Bed)  of 
the  Xew  Jersey  Cretaceous. 

This  form  is  very  similar  to  PolymorpTiina  lactea  from  which  it  is 
with  difficulty  separated.  Its  distribution  is  probably  the  same,  both 
recent  and  fossil. 

Occurrence. — Xanjemoy  Formation.  Woodstock.  Aquia  Forma- 
tion. Upper  Marlboro,  Brooks  Estate  near  Seat  Pleasant. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

PoLYMORPHiNA  LACTEA  (Walker  and  Jacob). 

Plate  LXIII,  Fig.  13. 

Serpida  lactea  Walker  and  Jacob,  1798,  Adam’s  Essays  (Kanmacher’s  Edit.)  p.  634, 
pi.  xxiv,  fig.  4. 

Poly t nor phina  lactea  Williamson,  1858,  Recent  Foram.  Gt.  Brit.,  p.  71,  pi.  vi,  fig.  147. 

Polymorphina  lactea  Brady,  Parker  and  Jones,  1870,  Trans.  Linn.  Soc.  London,  vol. 
xxvii,  p.  213,  pi.  xxxix,  fig.  1,  a-c. 

Description. — Test  ovate  or  subpyriform,  only  slightly  depressed,  con- 
sisting of  three  or  four  chambers  with  flush  sutures  and  scarcely  distinct 
septal  lines;  aperture  terminal,  radiate;  diameter,  0.39  mm.  (Miocene). 

It  is,  as  pointed  out  above,  very  difficult  to  separate  this  form  from 
P.  gilla.  It  is  somewhat  more  graceful  and  slender  and  less  obtuse  and 
the  MTiter  believes  that  there  is  less  good  ground  for  separating  these 
two  forms  than  for  distinguishing  Polymorphma  communis  and  Poly- 


MAKYLAXD  GEOLOGICAL  SUEVEY 


249 


morphina  problema.  The  description  of  this  form  precedes  P.  gibba  by 
nearly  50  years  and  if  any  change  is  made  this  must  be  given  the  prefer- 
ence and  P.  gibba  be  made  a variety  of  Poly  morphina  lactea.  Inasmuch 
as  there  is  jnst  as  great  danger  of  placing  together  many  forms  with 
varietal  distinctions  as  there  is  in  making  too  many  species  it  is  not  at- 
tempted at  the  present  time  to  change  previous  determinations  and 
specific  names.  While  fonnd  in  almost  every  sea  it  is  more  abundant  in 
the  shallow  waters  of  temperate  latitudes.  It  was  not  dredged  by  the 
Challenger  in  the  North  Atlantic  at  a greater  depth  than  400  fathoms 
but  in  the  South  Atlantic  was  fonnd  at  1990  fathoms,  North  Pacific  at 
2300  fathoms.  South  Pacific,  2350;  hut  in  all  these  cases  the  specimens 
are  rare  and  of  exceedingly  small  size,  showing  that  they  belong  to  shal- 
low water  temperate  zoneal  forms.  Its  geological  range  is  likewise  wide 
and  has  been  repeatedly  recorded  from  the  Jura,  Cretaceous,  and  the 
various  Tertiary  deposits.  It  has  been  fonnd  in  the  Miocene  of  Plum 
Point,  where  it  is  rare. 

Occurrence. — Aquia  Foematiox.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

PoLYMOEPHiNA  PEAELONGA  Terquem. 

Plate  LXIII,  Fig.  14. 

Polymorphina  praelonga  Terquem,  1878,  Mem.  Soc.  geol.  France,  series  3,  ^vol.  i, 
p.  39,  pis.  iii,  viii,  figs.  20,  21. 

Polymorphina  praelonga  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  92. 

Polymorphina  praelonga  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  31. 

Description. — Test  elongate  oval,  attenuated  anteriorly;  smooth  and 
glistening;  nearly  circular  in  transverse  section;  three  or  four  slightly 
raised,  elongate  chambers  marked  by  somewhat  depressed  septa.  Length, 
0.79  mm. 

This  species,  with  its  many  varieties  of  form,  is  beautifully  illus- 
trated in  Terqnem’s  Monograph  on  the  Eocene  Foraminifera  about 
Paris. 

It  is  said  to  he  more  abundant  in  the  Eocene  hut  quite  rare  in  de- 
posits of  (later)  Pliocene  age. 

Occurrence. — Nanjemoy  Foemation.  Woodstock. 

Collection. — Johns  Hopkins  University. 


250 


SYSTEMATIC  PALEONTOLOGY 


Family  GLOBIGERINIDAE. 

Genus  GLOBIGERINA  d’Orhigny. 

Globigerina  bulloides  cEOrbigny. 

Plate  LXIII,  Figs.  15,  16,  16a. 

Globigerina  bulloides  d’Orbiguy,  1826,  Ann.  Sci.  Nat.,  voi.  vii,  p.  277,  No.  1 ; 
Modeles,  No.  17  (young),  and  No.  76. 

Globigerina  bulloides  d’Orbigny,  1846,  Foram.  Fossiles  Vienne,  p.  163,  pi.  ix,  figs. 
4-6. 

Globigerina  bulloides  Brady,  1884,  Cbal.  Kept.,  vol.  ix,  p.  593,  pi.  Ixxvii,  and 
pi.  Ixxix,  figs.  3-7. 

Globigerina  bulloides  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  92. 

Globigerina  bulloides  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  33. 

Description. — Test  spiral,  siibtrochoid;  superior  surface  convex,  in- 
ferior more  or  less  convex  but  with  deeply-sunken  umbilicus;  periphery 
rounded,  lobulated;  adult  specimens  composed  of  about  seven  globose 
segments,  of  which  four  form  the  outer  convolution,  the  aperture  of  the 
individual  chambers  opening  independently  into  the  umbilical  vestibule; 
diameter  sometimes  one-fortieth  of  an  inch  (0,63  mm.),  but  oftener 
much  less.’^  (Brady,  loc.  cit.) 

While  this  species  is  not  uncommon  in  the  New  Jersey  Cretaceous  it 
is  rare  in  the  Eocene.  In  New  Jersey  in  the  Manasquan  (Upper  Marl 
Beds)  formation  it  is  however  much  larger  than  in  the  Rancoeas,  and.  is 
0.4  mm.  in  diameter  in  some  specimens. 

In  the  Miocene  of  Maryland  and  Virginia  it  is  also  rather  common 
but  it  is  most  abundant  in  the  Miocene  shell  marls  of  Plum  Point. 

In  present  oceans  this  species  of  Glohigerina  is  the  commonest  of  all 
the  Globigerinidae.  In  temperate  zones  it  exists  in  enormous  abundance 
and  it  does  not  seem  to  be  limited  in  depth  but  occurs  in  dredgings  all 
the  way  from  shallow  bottoms  to  the  greatest  depths.  It  is  one  of  the 
few  foraminifera  which  are  truly  pelagic  in  habit,  that  is,  exist  at  the 
surface  or  in  mid-water,  for  strange  as  it  may  seem,  the  majority  of 
genera  pass  their  existence  at  or  near  the  bottom.  Notwithstanding 
this  fact  that  the  great  majority  of  foraminifera  pass  their  existence 
near  the  bottom,  the  surface  and  middle  water  forms,  far  surpass  the 
former  in  point  of^numbers  and  are^resent  in  countless  millions  in  all 
great  oceans.  It  is  interesting  to  note  what  genera  and  species  belong 


^^rAEYLAXD  GEOLOGICAL  SURVEY^ 


251 


to  these  surface  forms  and  Professor  Brady  has  prepared  a list  to  show 
this  feature.  In  this  list  we  find  seven  species  of  Globigerinae,  Orbiilina 
iiniversa,  Ilastigeriua  pelagica,  PuUema  ohliquiloculata,  Sphaeroidina  de~ 
hiscens,  Candeina  nitida,  six  species  of  Pnlvinulina,  CymhaJopora  hul- 
loides  and  CliilostomeUa  ovoidea  Eeuss. 

Occurrence. — ISTaxjemoy^  Formatiox.  Woodstock,  Well  at  Chesa- 
peake Beach  at  90-92  feet. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

Family  ROTALIDAE. 

Genus  DISCORBINA  Parker  and  Jones. 

Discorbixa  bertheloti  (d’Orhigny). 

Plate  LXIY,  Fig.  1. 

Rosalina  bertheloti  d’Orbigny,  1839,  Foram.  Canaries,  p.  13.5,  pi.  i,  figs.  28-30. 

I>isco7'bina  bertheloti  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  9S. 

Discorbina  bertheloti  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  34. 

Description. — Test  very  compressed,  carinate,  finely  punctate;  spiral 
side  approximately  flat,  reverse  side  low-convex;  chambers  depressed,  nu- 
merous, convex,  margins  slightly  limbate;  ultimate  chamber  larger  than 
the  one  preceding.  The  shell  is  quite  similar  to  Truncatulma  lobatula, 
but  it  is  more  depressed,  and  the  walls  are  more  finely  perforate;  diame- 
ter, 0.42  mm. 

This  is  a shallow-water  f oraminif era  occurring  usually  at  depths  of 
less  than  500  fathoms. 

Occurrence. — Xaxjemoy  Formatiox.  Woodstock. 

Collection. — Johns  Hopkins  University. 

Discorbixa  turbo  (d’Orbigny). 

Plate  LXIV,  Fig.  2. 

Rotalia  {Troehulina)  turbo  d’Orbiguy,  1826,  Ann.  Sci.  Nat.,  vol.  vii,  p.  274,  No.  29; 
Modele,  No.  73. 

JJiscorbina  turbo  Parker,  Jones  and  Brady,  1865,  Ann.  and  Mag.  Nat.  Hist.,  series  3, 
vol.  xvi,  p.  30,  pi.  ii,  fig.  68. 

Discorbina  turbo  Brady,  1884,  Chal.  Kept.,  vol.  ix,  p.  642,  pi.  Ixxxvii,  figs.  8,  a,  b,  e. 

Description. — Test  solidly  built  in  a compact  involute  subconical  form; 
walls  rather  coarsely  perforated;  six  chambers  visible  on  inferior  surface 


t 

\ 


I 


252 


SYSTEMATIC  PALEONTOLOGY 


with  straight  depressed  septa  between  them  and  with  the  margin  slightly 
lohnlated  at  their  extremities.  The  inferior  surface  is  flat  or  nearly 
so;  superior  side  convex  and  several  (three?)  convolutions  indistinctly 
visible. 

Septal  lines  rather  sharply  and  gracefully  curved  and  less  definite  as 
the  primordial  chamber  is  reached,  which  makes  it  difficult  to  tell  how 
many  chambers  are  present.  Peripheral  view  a definite  cone  and  aper- 
ture lying  underneath  the  margin.  Shell  is  of  small  size  hut  is  very 
abundant  in  the  Lower  Eocene. 

This  species  is  found  in  the  Chalk  of  Maastricht  (Parker  and  Jones), 
the  Eocene  of  Paris  (Terquem),  etc. 

It  is  a shallow-w^ater  foraminifera  as  is  proved  by  the  Challenger 
expedition  which  obtained  the  form  at  420  fathoms  (Ascension  Island 
small  forms),  350  fathoms  off  the  coast  of  South  America,  at  from 
two  to  ten  fathoms  at  Port  Jackson,  Australia,  and  in  the  Bermuda 
coral  sands. 

Occurrence. — Aquia  Eokmation.  Upper  Marlboro. 

Collection. — Maryland  Geological  Survey. 

Genus  TRUNCATULINA  d’Orbigny. 

Truncatulina  lobatula  (Walker  and  Jacob). 

Plate  LXIV,  Fig.  3. 

N’autihts  lobatulus  Walker  and  Jacob,  1798,  Adam’s  Essays  (Kanmacher’s  Edit.), 
p.  642,  pi.  xiv,  fig.  36. 

TrimcatuUna  lobatula  Brady,  1884,  Chal.  Kept.,  vol.  ix,  p.  660,  pi.  xcii,  fig.  10; 
pi.  cxv,  figs.  4,  5. 

Truncatulina  lobatula  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  92. 

Truncatulina  lobatula  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  35. 

Description. — Test  plano-convex,  moderately  vaulted;  last  volution 
consisting  of  seven,  eight,  or  nine  chambers  with  slightly  depressed 
septa;  septa  more  curved  upon  the  superior  (flat)  surface;  aperture  a 
small,  neatly-shaped  arch  at  the  margin  of  the  ultimate  segment.  Diam- 
eter, 0.6  mm. 

Truncatulina  lohatula  shows  great  variation.  Professor  Brady  con- 
siders that  the  more  convex  varieties  merge  into  Truncatulina  refulgens, 


MARYLAND  GEOLOGICAL  SURVEY 


253 


while  flattened  forms  resemble  Truncatulina  wueJlerstorfi.  The  regular 
built  convex  varieties  constitute  Truncatulina  boueana  d’Orbigny  and 
the  less  regular  form  the  Truncatulina  variabilis  of  the  same  author. 
T.  variabilis  is  very  well  represented  in  the  Miocene  deposits  at  Plum 
Point,  and  elsewhere  in  the  Atlantic  Slope  Miocene. 

Truncatulina  lobatula  is  probably  the  most  widely  distributed  of  all 
the  Foraminifera.  In  present  oceans  it  occurs  in  every  latitude  from 
the  Arctic  waters  to  the  Antarctic  Ice  barrier.  It  is  most  frequent  in 
shallow  waters  but  is  present  also  at  depths  of  3000  fathoms. 

Its  geological  distribution  begins  with  compact  solid  forms  as  far  back 
as  the  Carboniferous  and  it  is  recorded  in  subsequent  formations  down 
to  the  present  day. 

Occurrence. — Xaxjemoy  Formation.  Woodstock.  Aquia  Forma- 
tion. Upper  Marlboro. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

Truncatulina  ungeriana  (d’Orbigny). 

Plate  LXIV,  Fig.  4. 

JRotalina  iingeriana  d’Orbigny,  1846,  Foram.  Fossiles  Vienne,  p.  157,  pi.  viii,  tigs. 

16-18. 

Truncatulina  linger iana  Brady,  1884,  Clial.  Kept.,  vol.  ix,  p.  664,  pi.  xciv,  fig.  fi,  a-r/. 

Description. — Test  large,  rotaliform,  circular,  coarsely  porous,  both 
sides  moderately  convex,  unequal,  depressed  slightly  on  the  inferior  side 
at  the  umbilicus;  consisting  of  three  convolutions.  The  last  \olution 
composed  of  ten  to  twelve  chambers.  Septa  arched;  aperture  a median 
slit  of  semilunar  shape.  Diameter,  0.T8  mm. 

This  species  is  common  in  the  Rancocas  formation  of  the  New  Jersey 
Cretaceous  and  it  is  fairly  abundant  in  the  Lower  Eocene  of  Upper  Marl- 
boro, near  Seat  Pleasant  and  elsewhere. 

In  the  Xorth  Atlantic  Truncatulina  ungeriana  is  fairly  abundant  at 
from  90  to  600  fathoms,  and  while  it  has  been  found  in  the  South  Pa- 
ciflc  at  depths  from  27  to  2600  fathoms  it  is  nevertheless  a shallow-water 
form.  Specimens  occur  in  the  Lower  Eocene  of  Pegwell  Bay,  England 
(Burrows)  and  in  the  London  Clay,  and  it  is  recorded  in  the  later  Ter- 
tiaries  of  southern  Europe. 


254 


SYSTEMATIC  PALEONTOLOGY 


Occurrence. — Aquia  Formation.  Upper  Marlboro,  Brooks  Estate 
near  Seat  Pleasant,  Well  at  Chesapeake  Beach  at  90-92  feet. 

Collection. — Maryland  Geological  Survey. 

Genus  ANOMALINA  d’Orbigny. 

AnOM ALINA  AMMONOIDES  (Eeuss). 

Plate  LXIV,  Fig.  5. 

Romlina  ammonoides  Reuss,  1845-46,  Verstein.  bohm.  Kreide,  i,  p.  36,  pi.  viii, 
fig.  53  ; pi.  xiii,  fig.  66. 

Anomalina  ammonoides  Bradj^  1884,  Cbal.  Kept.,  vol.  ix,  p.  672,  pi.  xciv,  figs.  2,  3. 

Anomalina  ammonoides  Bagg,  1898,  Bull.  88,  U.  S.  Geol.  Survey,  p.  67,  pi.  vi,  fig.  5. 

Description. — Test  nautiloid,  coarsely  porous,  small,  compressed;  lat- 
eral surface  nearly  equally  convex;  depressed  at  the  umbilici;  peripheral 
edge  round;  aperture  an  arched  nearly  median  opening  upon  the  inner 
margin  of  the  ultimate  segment.  Diameter,  0. 5-0.8  mm. 

In  the  Xorth  Atlantic  off  Bermuda  good  specimens  of  Anomalina 
ammonoides  were  taken  by  the  Challenger  expedition  but  no  other  speci- 
mens were  found  in  the  North  Atlantic.  These  were  at  the  depth  of 
435  fathoms.  It  was  recognized  in  dredgings  in  the  South  Pacific  at 
the  depths  of  210  fathoms  (near  the  Fiji  Islands),  also  at  1350  fathoms 
from  the  same  vicinity,  275  fathoms  off  New  Zealand,  and  another  in 
Humboldt  Bay  at  37  fathoms.  Parker  and  Jones  obtained  it  from  the 
Red  Sea  at  depths  of  372  and  678  fathoms,  also  in  anchor  muds  near 
Ilong  Kong  and  shore  sands  at  Melbourne.  It  is  common  as  a fossil 
from  Cretaceous  time  on  through  the  Tertiaries. 

Occurrence. — Aquia  Formation.  Upper  Marlboro. 

Collections. — Johns  Hopkins  University,  Maryland  Geological  Survey. 

Anomalina  grosserugosa  (Gtimbel). 

Plate  LXIV,  Fig.  6. 

Trmicatulina  (jrosserugosa  Giimbel,  1868,  Abhandl.  d.  k.  bayer.  Akad.  Wiss.,  vol.  x, 
p.  660,  pi.  ii,  fig.  104,  a,  h. 

Anomalina  grosserugosa  Brady,  1884,  Cbal.  Rept.,  vol. fix,  p.  673,  pi.  xciv,  figs.  4,  5. 

Anomalina  grosserugosa  Slierborn  and  Chapman,  1889,  Jour.  Royal  Microsc.  Soc., 
p.  487,  pi.  xi,  fig.  24. 

Anomalina  grosserugosa  Bagg,  1898,  Bull.  88,  U.  S.  Geol.  Surve}',  p.  67, 'pi.  vi,  fig.  4. 

Description. — Test  nautiloid,  very  coarsely  porous,  pores  larger  and 
more  numerous  upon  the  inferior  surface;  both  sides  convex;  umbilici 


MARYLAND  GEOLOGICAL  SURVEY 


distinct;  peripheral  margin  round;  chambers  large,  inflated;  only  eight 
in  final  convolution;  septa  nearly  straight;  aperture  median,  arched. 
Diameter,  0.43-0.82  mm. 

Though  occurring  in  the  Cretaceous  the  form  is  more  frequently  re- 
corded in  Tertiary  deposits.  Good  recent  specimens  were  secured  by 
the  Challenger  in  the  Xorth  Atlantic  at  depths  of  450  to  1000  fathoms, 
in  the  South  Atlantic  at  420  to  1415  fathoms,  in  the  South  Pacific  at 
610  and  2160  fathoms,  and  in  the  I^orth  Pacific  at  325  and  2050  fathoms. 

Occurrence. — Aquia  Formation.  1 mile  northeast  of  Piscataway. 

Collection. — Maryland  Geological  Survey. 

Genus  PULVINULINA  Parker  and  Jones. 

PULVINULINA  EXIGUA  VAR.  OBTUSA  BurrOWS. 

Plate  LXIV,  Fig.  7. 

Pnlvinnlina  exigua  var.  ohtusa  Burrows,  1S97,  Proc.  Geol.  Assoc,  (and  reprint),  vol. 

XV,  pts.  i,  ii  (Marcli-May),  p.  49,  pi.  ii,  tig-.  25  in  reprint. 

Description. — Test  free,  rotaliform;  both  faces  convex  and  generally 
equally  so;  composed  of  three  convolutions,  of  which  the  outermost  has 
usually  five  segments.  Sutures  non-limbate,  marked  on  the  superior 
face  by  thickened  lines  of  opaque  shell-substance;  on  the  inferior  by 
slight  depressions;  periphery  olfiuse,  and  very  rarely  lobulated.’’  Bur- 
rows, 1897. 

According  to  the  above  author  P.  exigua  var.  ohtusa  is  next  to  Bull- 
mina  elongata  the  most  common  foraminifera  of  the  Thanet  Sands 
(Lower  Eocene). 

Our  specimens  agree  closely  with  the  figure  of  Burrows’  varieties  of 
Pulvinulina  exigua  as  figured  by  Professor  Brady,  but  there  are  six  in- 
stead of  five  chambers  in  the  final  convolution  and  the  form  is  not  quite 
so  obtuse  as  the  type  forms.  The  perfectly  straight  septa  so  obliquely 
set  upon  the  superior  surface  are  more  distinct  in  the  outer  convolution. 
Upon  the  inferior  side  these  run  straight  to  the  center  of  the  umbili- 
cus. The  type  of  the  species  {P.  exigua)  is  regarded  as  a deep  water 
form.  In  the  Challenger  expedition  it  v'as  obtained  at  depths  ranging 


256 


SYSTEMATIC  PALEONTOLOGY 


from  64  to  2740  fathoms  but  it  is  quite  possible  that  this  variety  of  the 
form  is  not  to  be  so  regarded. 

Occurrence. — Aquia  Fokmation.  1 mile  northeast  of  Piscataway. 

Collection. — Maryland  Geological  Survey. 

PuLViNULiNA  SCHREIBEESII  (d’Orbigny). 

Plate  LXIV,  Fig.  8. 

Eotalina  schreihersii  d’Orbigay,  1846,  Foram.  Fossiles  Vienne,  p.  154,  pi.  vii,  tigs, 
4-6. 

Pulvinulina  schreiberaii  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  92. 

Palvinnlina  schreihersii  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  37,  pi.  xxiii,  tig.  2. 

Description. — Test  orbicular,  superior  side  more  convex  than  inferior; 
consisting  of  about  seven  chambers  in  the  final  convolution  (some  speci- 
mens show  nine);  inferior  side  distinctly  stellate  with  depressed  septal 
lines  and  elevated  chambers,  the  latter  feature  being  characteristic  for 
the  species  and  distinguishing  it  from  Pulvinulina  harsteni,  by  lack  of 
peripheral  keel.  The  final  chamber  is  larger  and  more  globose  than  the 
one  adjoining;  umbilicus  depressed  on  the  inferior  side;  aperture  a sub- 
marginal slit;  diameter,  0.4-0.54  mm. 

This  species  is  not  uncommon  in  the  Eocene  of  Woodstock  but  seems 
to  be  quite  rare  in  the  Miocene  of  James  Kiver,  Ya. 

Eeferring  to  the  depth  at  which  this  species  is  found  in  present  oceans 
Professor  Brady  says  in  the  Challenger  Eeport — off  New  Hebrides 
125  fathoms;  off  Ki  Islands,  129  fathoms;  southwest  of  Papua,  28  fath- 
oms; oft  Eaine  Island,  155  fathoms;  off  Cape  York,  Torres  Strait,  3-11 
fathoms;  Humboldt  Bay,  Papua,  37  fathoms;  and  off  Admiralty  Islands, 
17  fathoms;  ...  off  Bermuda,  435  fathoms.  Parker  and  Jones  record 
its  occurrence  in  the  Eed  Sea,  40  fathoms,  and  in  the  Mediterranean, 
90  fathoms.^^ 

Occurrence. — Hanjemoy  Formation.  Woodstock,  lYell  at  Chesa- 
peake Beach  at  90-92  feet. 

Collections. — Johns  Hopkins  Universit}^  Maryland  Geological  Survey. 


MARYLAND  GEOLOGICAL  SURVEY 


257 


Genus  NONIONINA  d’Orbigny. 

Nonionina  afeinis  Eeuss. 

Plate  LXIV,  Fig.  9. 

Nonionina  affitiis  Reuss,  1851,  Sitzungsb.  d.  k.  Akad.  Wiss.  Wien,  vol.  iii,  p.  72, 
pi.  Vj  flg.  32. 

Nonionina  affinis  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  92. 

Nonionina  affinis  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  39,  pi.  i,  fig.  5. 

Description. — Test  small,  orbicular,  strongly  compressed,  umbilicate, 
finely  perforate;  chambers  ten  to  twelve,  small,  fiat,  slightly  curved,  sep- 
arated by  fairly  distinct  band-like  septal  lines;  septal  plane  of  ultimate 
chamber  somewhat  higher  than  broad  and  quite  large;  aperture  short, 
semilunar.  Diameter,  0.32  mm.  Professor  Eeuss’  figure  agrees  fairly 
well  with  our  specimens  but  there  are  twelve  chambers  visible  in  the 
last  volution.  According  to  Eeuss  this  species  is  closely  related  to 
Nonionina  punctata  d’Orbigny,  but  the  latter  is  thicker  in  transverse 
section. 

Occurrence. — Xanjemoy  Formation.  Woodstock. 

Collection. — Johns  Hopkins  University. 

Genus  AMPHISTEGINA  d’Orbigny. 

Amphistegina  lessonii  d’Orbigny. 

Plate  LXIV,  Fig.  10. 

Amphistegina  lessonii  d’Orbigny,  1826,  (parte)  Ann.  Sci.  Nat.,  vol.  vii,  p.  304,  No.  3, 
pi.  xvii,  figs.  1-4. 

Amphistegina  lessonii  Brady,  1884,  Chal.  Kept.,  vol.  ix,  p.  740,  pi.  cxii,  figs.  1-7. 

Amphistegina  lessonii  Bagg,  1896,  Bull.  141,  U.  S.  Geol.  Survey,  p.  92. 

Amphistegina  lesso7iii  Bagg,  1898,  Bull.  Amer.  Pal.,  No.  10,  p.  42,  pi.  i,  fig.  6. 

Description. — Test  circular,  compressed,  transverse  elliptical;  superior 
only  slightly  more  elevated  than  the  inferior;  superior  surface  shows 
about  eighteen  angular  segments;  inferior  surface  less  distinctly  cham- 
bered, more  irregular;  chambers  narrow,  angular,  visible  in  transmitted 
light;  surface  smooth  and  of  a brownish-yellow  color.  Diameter,  1.47-2 
mm. 

Professor  Brady  states  that  this  species  shows  great  variation  in  the 

amount  of  convexity.  Our  specimens  agree  more  closely  with  his  Fig.  4 
17 


258 


SYSTEMATIC  PALEONTOLOGY 


of  Plate  CVI,  in  the  Challenger  Eeport  and  may  be  considered  as  typical 
for  the  species.  This  is  not  a common  form  and  only  three  specimens 
have  been  obtained  at  Woodstock  and  only  a few  are  found  in  the  Mio- 
cene of  Darlington,  S.  C.,  nearly  all  of  which  are  imperfect  specimens. 

In  existing  oceans  this  form  is  commonest  on  bottoms  of  less  than  ^0 
fathoms  depth  and  is  rare  below  300  to  400  fathoms.  It  is  more  fre- 
quent in  warm  tropical  waters.  As  a fossil  it  has  been  variously  de- 
scribed from  the  Tertiaries  of  Europe,  among  them  being  the  Eocene  of 
the  Paris  Basin  (Terquem),  Upper  Eocene  of  the  Swiss  Alps  (Kauf- 
mann),  etc. 

Occurrence. — Uanjemoy  Eokmation.  Woodstock. 

Collection. — Johns  Hopkins  University. 

PLANTAE. 

Carpolithus  marylandicus  n.  sp. 

Plate  LXIV,  Figs.  11,  11a,  11b. 

Fruit  irregularly  ovate,  about  f inch  long,  broadest  at  the  base, 
4-valved  (?);  valves  separating  completely  to  the  base;  epicarp  rough, 
somewhat  warty,  wrinkled  or  ridged  longitudinally,  about  1-16  inch 
thick,  distinct  from  the  smooth  pericarp;  seed  cells  about  f inch  long 
by  -J  inch  broad,  attenuate  towards  the  apex  of  the  fruit  and  rounded 
at  the  base. 

Carpolithus  marylandicus  yar.  rugosus  n.  var. 

Plate  LXIV,  Figs.  12,  12a,  12b. 

Orbicular,  about  7-16  inch  in  diameter,  or  less;  warty,  but  without 
longitudinal  markings;  seed  cells  relatively  broader  to  the  length  than 
in  the  species. 

The  material  upon  which  the  descriptions  and  figures  of  Carpolithus 
are  founded  is  exceedingly  fragmentary,  not  one  entire  fruit  being  rep- 
resented in  the  collection.  The  drawings  of  the  complete  fruits  were 
made  by  fitting  together  disconnected  valves,  and  as  these  vary  in  size 


MARYLAND  GEOLOGICAL  SURVEY 


259 


the  number  of  yalves  into  which  the  fruit  was  actually  divided  is  un- 
certain. They  may  have  been  three  or  four  or  five,  and  for  that  reason 
the  number  is  questioned  in  the  description. 

The  fruit  resembles  quite  closely  Pliymatocoryon  mackayi  Muell.,  from 
the  auriferous  drifts  of  Australia,  described  in  the  Eeport  of  the  Geo- 
logical Survey  of  Victoria  for  1874,  p.  11,  pi.  ii,  which  is  however  defi- 
nitely 3-valved.  The  geological  horizon  of  these  drifts  is  considered 
as  Pliocene. 

In  this  connection  it  may  be  of  interest  to  note  that  the  fossil  fruit 
deposit  of  Brandon,  Vt.,  described  by  Hitchcock  (Commonwealth  of 
Massachusetts,  House  Document  Vo.  39,  1853,  pp.  22-34;  Amer.  Jour. 
Sci.,  vol.  XV,  1853,  pp.  95-104)  and  by  Lesquereux  (Kept.  Geology  of 
Vermont,  vol.  ii,  1861,  pp.  712-718;  Amer.  Jour.  Sci.,  vol.  xxxii,  1861, 
pp.  355-363)  has  been  called  by  different  authorities  Eocene,  Miocene, 
Pleiocene  and  Pleistocene. 

The  general  appearance  of  our  material  is  quite  similar  to  that  from 
Brandon,  being  thoroughly  lignitized,  with  the  general  form  of  the  fruit 
preserved.  The  internal  structure  has,  however,  been  more  or  less  de- 
stroyed or  altered  and  it  has,  therefore,  not  been  possible  to  determine 
satisfactorily  the  probable  botanical  affinities. 

The  only  other  record  with  which  I am  familiar,  of  similar  material 
from  the  United  States,  is  by  Edmund  Puffin  (Amer.  Jour.  Sci.,  ser.  ii, 
vol.  ix,  1850,  pp.  127-129)  describing  a fossil  nut  from  the  Eocene  marl 
of  Marlbourne,  Va. 

Vone  of  the  American  species  described  or  figured  may  be  satisfac- 
torily identified  with  our  specimens. 


I 


PLATES 


PLATE  X. 

PAGE 


Fig-s.  1,  2.  Tiiecachampsa  sp 95 

1.  Dorsal  view  of  dorsal  vertebra.  Liverpool  Point. 

2.  Posterior  view  of  same  specimen. 

Fig.  3.  Thecachampsa  sericodon  (?)  Coj)e  95 

Tooth.  Clifton  Beach. 

Fig.  4.  Thecachampsa  contusor  Cope 96 

4a.  Lateral  view  of  tooth.  Aqiiia  Creek. 

4b.  Basal  view  of  same  tooth. 

Fig.  5.  Thecachampsa  marylandica  Clark  96 

Fragment  of  jaw  with  tooth.  Clifton  Beach. 

Fig.  6.  Eeptilian  coprolite  96 

From  Clifton  Beach. 

Fig.  7.  Euclastes  (?)  sp 97 

Costal  plate.  Clifton  Beach. 


263 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  X. 


REPTILIA, 


PLATE  XI. 

PAGE 

Figs,  la,  lb.  Trionyx  virginiana  Clark  97 

Costal  plates.  Aqiiia  Creek.  Museum  Wagner  Free  lust.  Sci.,  Phila. 


263 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE 


REPTILIA. 


PLATE  XII. 

PAGE 

Figs.  1.  2.  Myliobatis  copeanus  Clark  99 

1.  Oral  aspect  of  upper  dental  plate  of  an  adult  individual.  The  an- 

terior end  is  uppermost.  Clifton  Beach. 

2.  Portion  of  lower  dental  plate  of  an  immature  individual,  showing 

two  rows  of  lateral  teeth  and  anterior  depression  due  to  wear. 
Clifton  Beach. 

Fig.  3.  Myliobatis  magister  Leidy 100 

Oral  aspect  of  a very  large  upper  dental  plate,  the  anterior  end  shown 
uppermost  in  the  figure.  Museum  Comp.  Zool.,  Cambridge.  Ashley 
River,  S.  C. 

Figs.  4-6.  Otolites  of  Teleostome  Fishes 113 

Pof)es  Creek.  X 4. 

Figs.  7a,  7b.  Detached  vertebral  centrum  of  an  indeterminate  Tele- 
ostome fish  110 

7a.  Lateral  view.  Clifton  Beach. 

7b.  End  view  of  same  specimen. 

Fig.  8.  XiPHiAS  (?)  RADIATA  (Clark)  112 

Llypural  fan  as  viewed  from  the  left  lateral  aspect.  Clifton  Beach. 


264 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XII. 


PISCES. 


PLATE  Xlll. 


PAGE 


Figs,  la,  lb.  Myliobatis  magister  Leidy  100 

la.  Transverse  surface  of  the  same  sj)ecimen  shown  in  Plate  XII, 

Fig.  3.  The  anterior  end  is  placed  uppermost  in  the  figure. 

lb.  Attached  surface  of  same  specimen. 

Figs.  2a,  2b.  Myliobatis  copeanus  Clark  99 

2a.  Transverse  section.  Liverpool  Point. 

2b.  Attached  surface,  same  locality.  The  anterior  end  is  f>laced  uiiper- 
most  in  the  figures. 

Figs.  3a,  3b.  Aetobatis  arcuatus  Agassiz  102 

3a.  Attached  surface  of  detached  tooth.  Pof)es  Creek. 

3b.  Lateral  aspect  of  same  sxiecimen. 

Fig.  4.  Myliobatis  sp 101 

Transverse  and  longitudinal  views  of  caudal  siiine,  Ashley  lliver,  S.  C. 
Museum  Comp.  Zook,  Cambridge. 

Fig.  5.  Myliobatis  sj) 101 

Transverse  and  longitudinal  views  of  caudal  spine,  Montgomery,  La. 
Museum  Coinj).  Zook,  Cambridge. 

Figs.  6,  7a,  7b.  Myliobatis  copeanus  Clark 99 

6.  Nearly  jierfect  uxif)er  dental  xilate  of  a comxjaratively  young  indi- 
vidual; the  anterior  end  shown  up^iermost  in  the  figure.  Clifton 
Beach. 

7a.  Oral  surface  of  lower  dental  i)late  of  a comjiaratively  young  indi- 
vidual with  serrated  sutures  due  to  wear.  Clifton  Beach. 

7b.  Inferior  asjiect  of  same  specimen. 


Fig.  8.  Aetobatis  arcuatus  Agassiz  

Oral  surface  of  a detached  tooth.  Popes  Creek. 


102 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XIII. 


PISCES. 


PLATE  XIV. 

PAGE 

Figs,  la,  lb.  Odontaspis  cuspidata  (Agassiz)  105 

la.  Inner  face  of  a tooth  with  well-developed  lateral  denticles.  Liver- 

pool Point. 

lb.  Outer  face  of  same  specimen. 

Figs.  2a,  2b,  2c,  3a,  3b,  3c.  Odontaspis  elegans  (Agassiz) 104 

2a.  Inner  face  of  a worn  anterior  tooth  lacking  its  pair  of  lateral 
denticles.  Liverpool  Point. 

2b.  Lateral  aspect  of  the  same  specimen. 

2c.  Outer  face  of  the  same  specimen. 

3a.  Inner  face  of  a well-preserved  tooth  showing  prominent  coronal 
striae.  Aquia  Creek. 

3b.  Lateral  asiiect  of  the  same  specimen. 

3c.  Outer  face  of  the  same  specimen. 


Figs.  4a,  4b.  Odontaspis  macrota  (Agassiz)  105 

4a.  Outer  face  of  a tooth.  Liverpool  Point. 

4b.  Inner  face  of  the  same  specimen. 

Figs.  5a,  5b,  5c.  Syneciiodus  clarkii  n.  sp 103 


5a.  Inner  face  of  a tooth.  Liverpool  Point. 
5b.  Lateral  aspect  of  the  same  specimen, 
5c.  Outer  face  of  the  same  specimen. 


Figs.  6a,  6b.  Odontaspis  cuspidata  (Agassiz)  105 

6a.  Outer  face  of  a tooth.  Liverpool  Point. 

6b.  Inner  face  of  the  same  specimen. 

Figs.  7a,  7b.  Sphyrna  prisca  Agassiz 110 

7a.  Inner  face  of  a tooth.  Liverxiool  Point. 

7b.  Outer  face  of  the  same  siiecimen.. 

Fig.  8.  Galeocerdo  latidens  Agassiz  109 

Outer  face  of  a tooth.  Woodstock.  X 2 


PISCES. 


PLATE  XV. 

PAGE 

Figs.  1-4.  Otodus  obliquus  Agassiz 106 

la.  Inner  face  of  an  anterior  tooth  belonging  to  an  immature  indi- 

vidual, and  corresponding  in  size  to  the  lateral  tooth  shown  in 
Fig.  5.  Liverpool  Point. 

lb.  Lateral  aspect  of  same  specimen. 

lc.  Outer  face  of  same  specimen. 

2a.  Inner  face  of  a lateral  tooth  belonging  to  an  immature  individual. 
Liverpool  Point. 

2b.  Lateral  aspect  of  same  specimen. 

2c.  Outer  face  of  same  specimen. 

3a.  Outer  face  of  a lateral  tooth,  with  a well-develox^ed  pair  of  lateral 
denticles.  Aquia  Creek. 

3b.  Lateral  aspect  of  same  specimen. 

3c.  Inner  face  of  same  specimen. 

4a.  Inner  face  of  an  unusually  large  and  massive  tooth  with  erect 
crown,  entire  edges  and  large  lateral  denticles,  showing  transi- 
tional characters  between  Carcliarodon  and  Larnna.  Glymont. 

4b.  Lateral  aspect  of  same  specimen. 

4c.  Outer  face  of  same  si^ecimen. 


PISCES. 


PLATE  XVI. 

Fig-s.  1-4.  Bythocypris  subaequata  n.  sp 

1.  Eight  side  of  an  entire  carapace.  Upper  Marlboro. 

2.  Dorsal  view  of  same. 

3.  Anterior  view  of  same. 

4.  Inner  side  left  valve  showing  internal  marginal  jilate. 

Figs.  5-8.  Bythocypris  parilis  n.  sp 

5.  Eight  side  of  entire  carapace.  Upper  Marlboro. 

6.  Ventral  edge  of  same. 

7.  Inner  side  of  right  valve. 

8.  Inner  side  of  left  valve. 

Figs.  9-13.  Cytiierella  marlboroensis  n.  sii 

9.  Left  side  of  a perfect  carapace.  Upper  Marlboro. 

10.  Eight  side  of  another  specimen  from  same  locality. 

11.  Dorsal  view  in  outline  of  same. 

12.  Inner  side  of  a right  valve. 

13.  Anterior  end  view. 

Figs.  14-15.  Cytherella  submarginata  n.  sp 

14.  A left  valve  showing  slight  mesial  depression  and  marginal 

Upper  Marlboro. 

15.  Ventral  view  of  same. 

Figs.  16-18.  Cythere  marylandica  n.  sp 

16.  Posterior  end  view  of  an  entire  caraxmce.  Upper  Marlboro. 

17.  Eight  side  of  same. 

18.  View  of  ventral  edge  of  same. 

Figs.  19-21.  Cythereis  bassleri  n.  sp 

19.  An  average  left  valve  of  this  species. 

20.  Ventral  edge  of  an  entire  carapace. 

21.  Outline  view  of  anterior  end  of  same. 

Figs.  22-23.  Cytheridea  perarcuata  n.  sp 

22.  View  of  a right  valve. 

23.  Ventral  edge  of  same. 

All  the  figures  are  magnified  20  diameters. 


268 


PAGE 

116 


117 


117 


118 

rim. 


119 


120 


121 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XVI. 


ARTHROPODA CRUSTACEA. 


PLATE  XVII. 

PAGE 

Hercoglossa  tuomeyi  n.  sp 122 

Lateral  view  of  smaller  tyi^e.  Popes  Creek.  X % 


269 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XVll- 


b 


MOLLUSCA CEPHALOPODA. 


PLATE  XV HI. 

PAGE 

Hercoglofsa  tuomeyi  n.  sp 122 

Lateral  view  of  larg-er  type,  showing  fragments  of  shell  substance  with 
lines  of  growth.  Popes  Creek.  X % 


270 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XVIII- 


MOLLUSCA CEPHALOPODA. 


PLATE  XIX. 

Fig-s.  1-3.  Hercoglossa  tuoaieyi  n.  sp 

1.  Peripheral  view  of  specimen  illustrated  on 

Creek. 

2.  Specimen  showing*  frag-ment  of  shell  substance 

Popes  Creek. 

3.  Specimen  showing*  a fragment  of  shell  from 

Clifton  Beach. 


PAGE 

122 

Plate  XVII.  Popes 
X % 

from  near  periphery. 
X % 

near  the  umbilicus. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XIX. 


MOLLUSCA CEPHALOPODA. 


PLATE  XX. 


PA<iE 

Fig-s.  1,  la,  2.  Tornatellaea  Bella  Conrad  123 

1.  A(|tiia  ('reek.  U.  S.  Xatioiial  Museimi. 
la.  Dorsal  view  of  same  specimen. 

2.  Aqiiia  ('reek.  Acad.  Xat.  Sei.  Pliila.  Lea  Memorial  Coll. 

Fig-.  3,  3a.  Kingicula  dallt  Clark  124 

3.  Dorsal  view.  (After  Clark.)  Woodstock. 

3a.  \'entral  view  of  same  sj)eeimen.  (After  Aldrich.) 

Figs.  4,  4a.  Cyliciina  yenfsta  Clark  124 

4.  Ventral  view  of  type  specimen.  Woodstock. 

4a.  Dorsal  view  of  same  specimen. 

Figs.  5,  5a,  6.  Plefrotoma  iiarrisi  Clark  125 

5.  5a,  Original  figures  of  type  specimen.  Potomac  Creek. 

6.  S])ecimen  with  more  distinct  scnl])tni‘e.  Same  locality. 

Figs,  7,  7a.  Plefrotoma  potomacensis  n.  sp 12(5 

7.  Ventral  vietv  of  type  s])ecimen.  2 miles  belotv  Potomac  Creek. 

7a.  Dorsal  view  of  type  specimen. 

Fig.  8.  Plefrotoma  dfcateli  n.  sp 12() 

Dorsal  view  of  type  s])ecimen.  1 mile  southeast  of  Mason  Sx>rings. 

Fig.  9.  Plefrotoma  tysoai  n.  sp 12G 

Ventral  view  of  type  s])ecimen.  1 mile  southeast  of  Mason  Springs. 

Figs.  10,  11.  Plefrotoma  gtiiloreni  Lea  127 

10.  Ventral  view  of  broken  sxtecimen.  1 mile  southeast  of  INlason 

Springs. 

11.  Dorsal  view  of  more  nearly  perfect  individual. 

Fig.  12,  Plefrotoma  ptscatavensis  n.  sp 127 

Dorsal  view  of  type  specimen.  1 mile  northeast  of  Piscataway. 

Figs.  13,  13a.  IMangilia  (Plefrotomella)  bellistrtata  Clark 128 

13.  Ventral  view  of  ty]te  s])ecimen,  enlarged  as  indicated.  Popes  Creek. 
13a.  Dorsal  view  of  same  sjtecimen,  natnral  size. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XX. 


4 


MOLLUSCA— CEI>HAL()l'OI).\. 


PLATE  XXI. 


PAGE 

Fig.  1.  Cancellaria  graciloides  Aldrich  var 128 

Ventral  view  of  specimen  from  1 mile  southeast  of  Mason  Springs. 

Fig.  2.  Cancellaria  sp 129 

Much  enlarged  view  of  specimen  from  2 miles  below  Potomac  Creek. 

Figs.  3,  3a.  Cancellaria  (Narona)  potomacensis  n.  sp 129 

3.  Ventral  view  of  specimen  from  1 mile  northeast  of  Piscataway. 

3a.  Dorsal  view  of  same  sj)ecimen. 

Pigs.  4,  5,  5a.  Volutilithes  petrosus  (Conrad)  130 

4.  Pomonkey  Neck.  U.  S.  National  Museum. 

5.  Dorsal  view.  Potomac  Creek. 

5a.  Ventral  view  of  same  specimen. 

Figs.  6,  6a.  Volutilithes  sp 131 

6.  Ventral  view  of  cast.  Aqnia  Creek. 

6a.  Dorsal  view  of  same  specimen. 

Figs.  7,  S.  Caricella  pyruloides  (?)  (Conrad)  131 

7.  Spire  and  part  of  body  whorl.  Potomac  Creek. 

8.  Cast.  Aqnia  Creek. 

Figs.  9,  9a.  Mitra  marylandica  Clark  132 

9.  Dorsal  view.  Pomonkey  Neck.  U.  S.  National  Museum. 

9a.  Ventral  view  of  same  specimen. 

Figs.  10,  10a.  Mitra  pomonkensis  n.  sp 132 

10.  Ventral  view.  Pomonkey  Neck.  U.  S.  National  Museum. 

10a.  Dorsal  view  of  same  specimen. 

Fig.  11.  Mitra  potomacensis  n.  sp 133 

Enlarged  view.  1 mile  northeast  of  Piscataway. 

Figs.  12,  12a.  Latiriis  marylandicus  n.  sp 133 

12.  Ventral  view.  2 miles  below  Potomac  Creek. 

12a.  Dorsal  view  of  same  speeimen. 


J73 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXI. 


MOLLUSCA GASTROPODA. 


PLATE  XXII. 


PAGE 

134 


Figs.  1,  2.  Fusus  (?)  si'BTENX'is  ITeilprin 

1.  Dorsal  view  of  specimen  with  nearly  ])erfeet  spire.  2 miles  below 

Potomac  Creek. 

2.  Ventral  view  of  another  specimen  with  perfect  month.  Two  miles 

below  Potomac  Creek. 

Fig.  3.  Tropiion  sublevis  Harris  135 

\hew  of  fragment,  with  outlined  restoration.  1 mile  northeast  of 
Piscataway. 

Figs.  4,  4a.  Fx^stis  (?)  interstriatits  Heilprin 135 

4.  Ventral  view  of  specimen.  1 mile  northeast  of  Piscataway. 

4a.  Dorsal  view  of  same  sjxecimen. 

Figs.  5-8.  Strepsidura  subscalarina  Heilprin  136 

5,  6.  Ventral  views  of  specimens.  2 miles  below  Potomac  Creek. 

7.  Potomac  Creek.  Acad.  Xat.  Sci.  Phila. 

8.  Ventral  view.  2 miles  below  Potomac  Creek. 

8a.  Dorsal  view.  Same  locality. 

Fig.  9.  MELONGENA  (?)  POTOMACENSTS  11.  sp 136 

Type.  Potomac  Creek.  Acad.  Xat.  Sci.  Phila.  Lea  .Memorial  Coll. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXII. 


M ( ) LLU  S C A G A ST  R O P (3 1)  A . 


PLATE  XXIII. 

PAGE 


Fig'S,  1,  la,  lb.  Tudicla  marylandica  n.  sp 137 

Ventral,  dorsal  and  end  views.  2 miles  below  Potomac  Creek. 

Fig'S.  2,  2a.  Tudicla  sp 138 

Ventral  view.  Crownsville. 

End  view  of  the  same  specimen. 

Fig-.  3.  Levifusus  trareatus  (?)  Conrad  var 139 

Cast.  Woodstock. 

Fig'.  4.  Tudicla  (?)  sp 138 

Cast.  Aquia  Creek. 

Fig.  5.  Metula  marylandica  n.  sp 139 

Ventral  view  of  type  specimen.  2 miles  below  Potomac  Creek. 

Fig.  6.  Chrysodomus  engonatus  (Heilprin)  140 

2 miles  below  Potomac  Creek. 

Fig.  7.  PSEUDOLIVA  sp 140 

Cast.  Upper  Marlboro. 


375 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXIII. 


MOLLUSCA — GASTROPODA. 


PLATE  XXIV. 


Figs.  1,  la.  Tritonii'm  siiowalteki  ((’oiirad)  141 

1.  Ventral  view.  2 miles  below  Potomae  Creek, 
la.  Dorsal  view  of  the  same  specimen. 

Fig.  2.  Pykula  PENiTA  var.  Conrad  131 

Ventral  view  with  outlined  restoration.  Popes  Creek. 

Figs.  3,  3a.  Fulgukoficus  argutus  Clark  142 

Type  specimen.  I’otomac  Creek. 

Figs.  4,  la.  Fusoficula  juvenis  (Whitfield)  143 

4.  Ventral  view.  2 miles  below  Potomae  Creek. 

4a.  Dorsal  view  of  the  same  specimen. 

Fig.  5.  Pyrula  (?)  sp.  112 

Body  whorl.  Ponies  Creek. 

Fig.  C.  Tfdk'la  (?)  s]) 138 

Po])es  Creek. 

Morio  rrevidentata  (Aldrich)  144 

Dorsal  view.  1 mile  southeast  of  IMason  Springs. 

Fig.  8.  Cypraea  SMiTiii  Aldrich  144 

Specimen  with  outlined  restoration,  mile  belo\v  Cha])el  Point. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXIV. 


3 


MOLLUSCA GASTROPODA. 


PLATE  XXV. 

PAGE 

Fig’S.  1,  la,  2.  Calyptraphorus  jacksoni  Clark 145 

1.  Dorsal  view  of  type.  Sheckels  Farm  near  South  Eiver. 
la.  Ventral  view  of  same  specimen. 

(Fig’S.  1 and  la  are  modified  and  corrected  copies  of  the  original 
figures  in  Bull.  141,  U.  S.  Geol.  Survey.) 

2.  Dorsal  view  of  large  individual  from  same  locality. 


Fig.  3.  Calyptraphorus  trinodiferus  Conrad  145 

Dorsal  view.  2 miles  below  Potomac  Creek. 

Figs.  4,  4a.  Calyptraphorus  trinodiferus  (?)  Conrad  var 146 

4.  Ventral  view.  1 mile  southeast  of  ISlason  Springs. 

4a.  Dorsal  view  of  the  same  specimen. 

Figs.  5,  6.  Aporrhais  potomacensis  n.  sp 146 


5.  Ventral  view  of  imperfect  individual.  Digitations  restored  from 

original  of  Fig.  6.  1 mile  northeast  of  Piscataway. 

6.  External  view  of  labruni  of  large  individual  from  same  locality. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXV. 


MOLLUSCA — GASTROPODA. 


PLATE  XXVI. 


PAGE 

Figs.  1-5.  Turkitella  mortoni  Conrad  147 

1.  Ventral  view  of  specimen.  Potomac  Creek, 
la.  Dorsal  view  of  same  specimen. 

2.  More  elong’ate  specimen  from  same  locality. 

3.  Specimen  from  same  locality  with  stronger  basal  carina. 

4.  Internal  cast. 

5.  Specimen  showing-  the  strong  basal  carina  of  the  variety  postmortonl 

of  Harris.  Tinkers  Creek. 


MARYLAND  GEOLOGICAL  SURVEY, 


EOCENE,  PLATE  XXVI 


MOLLUSCA GASTROPODA. 


PLATE  XXVII. 

PAGE 


Fig’S.  1,  la.  Turritella  iiumerosa  Conrad 148 

1.  Ventral  view.  1 mile  southeast  of  Mason  Springs. 

Figs.  2,  3.  Turritella  potomacensis  n.  sp 149 

T3^pe  specimens.  Popes  Creek. 

Fig.  4.  Mesalia  obruta  (Conrad)  149 

Popes  Creek. 

Figs.  5,  5a,  6,  7.  Vermetus  sp 150 

5.  Small  mass  of  tubes. 

5a.  End  of  same  tube,  enlarged. 


6.  Mass  of  tubes.  Piscataway  Creek.  U.  S.  National  Museum. 

7.  Short  fragment  of  tube  from  same  specimen,  enlarged. 


3T9 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXVII. 


5 


6 


MOLLUSCA GASTROPODA. 


PLATE  XXVIII. 

PAGE 


Fig-.  1.  Xatica  cliftonensis  Clark  150 

Ventral  view  of  type  sj)ecimen.  Clifton  Beaeli. 

Figs.  2,  2a,  3.  Lunatia  makylandica  Conrad  151 

Figs.  4,  5.  CAr.YPTEAEA  APERTA  (Solancler)  152 

4.  Dorsal  view  of  specimen.  1 mile  southeast  of  Mason  Springs. 

5.  Cast  of  large  individual. 

Figs.  6,  6a.  Litiopa  marylandica  n.  sp 152 

G.  Dorsal  view  of  type  specimen.  2 miles  below  Potomac  Creek. 

Figs.  7,  7a.  Solarium  sp 153 

7.  Cast,  as  seen  from  above.  Aquia  Creek. 

7a.  Same  specimen  as  seen  from  the  side. 

Figs.  8,  8a,  9,  9a.  Sc  ALA  virgintana  Clark  153 


8.  Ventral  view  of  type  specimen.  Ac|uia  Creek.  U.  S.  National 

Museum. 

8a.  Dorsal  \iew  of  same  specimen. 

9.  Ventral  view  of  sjiecimen.  Potomac  Creek.  Acad.  Nat.  Sci.  Phila. 
9a.  Dorsal  view  of  the  same  specimen. 


Fig.  10.  SCALA  POTOMACENSIS  n.  sp 154 

Type  specimen.  2 miles  below  Potomac  Creek. 

Pig.  11.  Sc  ALA  SESSILIS  Conrad  154 

2 miles  below  Potomac  Creek. 

Fig.  12.  ScALA  CARUSTATA  Lea  154 

2 miles  below  Potomac  Creek. 


280 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXVIII. 


MOLLUSCA GASTROPODA. 


PLATE  XXIX. 


*PAGE 


Fig-.  1.  TuRBONILLA  POTOMACENiSIS  n.  sp 155 

2 miles  below  Potomac  Creek. 

Fig-.  2.  Tuba  marylandica  n.  sp 155 

Mouth  of  Paspotansa  Creek. 

Fig.  3.  Odostomia  trapaquara  (Harris)  156 

Potomac  Creek. 

Fig.  4.  Niso  UMBiLiCATA  (Lea)  156 

Potomac  Creek. 

Fig.  5.  Gibbpla  glandula  (Conrad)  157 

Potomac  Creek. 

Figs.  6,  6a.  Fissuridea  marlboroensis  n.  sp 158 

6.  Lateral  view  of  type  specimen.  Upper  Marlboro. 

6a.  Dorsal  view  of  same  specimen. 

Fig.  7.  Dentalium  minutistriatum  Gabb  158 

Popes  Creek. 

Fig.  8.  Deintalium  mississippiensis  Conrad  159 

Upper  Marlboro. 

Fig.  9.  Cadulus  abruptus  Meyer  and  Aldrich  159 

Woodstock. 


281 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXIX. 


MOLLUSCA — -GASTROPODA  AND  SCAPHOPODA. 


PLATE  XXX. 

PAGE 

Figs.  1,  la.  Teredo  vieginiana  (?)  Clark 160 

1.  Lateral  view  enlarged  as  indicated, 
la.  End  view  of  same  specimen. 

Figs.  2,- 2a,  3.  Teredo  vieginiana  Clark 160 

2.  ETiteral  view  of  small  fragment  of  tube.  Woodstock. 

2a.  End  view  of  same  specimen. 

3.  Lateral  view  of  another  fragment.  Woodstock. 

Figs.  4,  4a,  4b.  Phenacomya  petrosa  (Conrad)  161 

4.  Dorsal  view  of  cast.  Fort  Washington. 

4a.  Same  specimen  as  seen  from  the  left. 

4b.  Same  specimen  as  seen  from  the  right. 

Fig.  5.  Gastrociiaena  sp 161 

Cast  of  tube.  Aqnia  Creek. 


383 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXX. 


MOLLUSCA PELECYPODA. 


PLATE  XXXI. 

PAGE 

Figs.  1-5.  Panopea  elongata  Conrad  162 

1.  Left  aspect  of  cast.  Fort  Washington. 

2.  Left  valve.  Aquia  Creek. 

2a.  Surface  of  same  specimen.  X 17 

3.  Light  valve  of  Fig.  1. 

4.  Left  valve.  Fort  Washington. 

5.  Light  valve.  Fort  Washington. 


283 


MARYLAND  GEOLOGICAL  SURVEY, 


EOCENE,  PLATE  XXXI. 


MOLLUSCA PELECYPODA. 


PLATE  XXXII. 


Figs.  1,  la,  2,  2a,  2b,  Corbula  subengonata  Dali 

1.  Exterior  of  right  valve.  Poises  Creek, 
la.  Interior  of  same  specimen. 

2.  Interior  of  left  valve.  Popes  Creek. 

2a.  Exterior  of  same  specimen. 

2b.  Hinge  of  same  specimen,  enlarged. 

Figs.  3,  3a,  4,  4a,  5,  5a,  6,  6a.  Corbula  alurichi  Meyer 

3.  Exterior  of  right  valve.  Evergreen,  Va. 

3a.  Interior  of  same  specimen. 

4.  Interior  of  left  valve.  Evergreen,  Va. 

4a.  Exterior  of  same  specimen. 

5.  Exterior  of  right  valve.  Evergreen,  Va. 

5a.  Interior  of  same  specimen. 

6.  Interior  of  yonng  left  valve.  Evergreen,  Va. 
6a.  Exterior  of  same  specimen. 

Figs.  7,  7a,  8,  8a,  8b.  Corbula  oniscus  Conrad 

7.  Interior  of  right  valve.  Evergreen,  Va. 

7a,  Exterior  of  same  specimen. 

8.  Dorsal  view  of  specimen.  Evergreen,  Va. 

8a,  Interior  of  right  valve  of  same  individual. 

8b.  Exterior  of  same  valve. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXXII. 


MOLLUSCA PELECYPODA. 


PLATE  XXXIII. 

PAGE 


Fig.  1.  SOLEN  LISBONENSIS  (?)  Alclrich  165 

Fragment  of  left  valve.  ^ mile  below  Chapel  Point. 

Figs.  2,  2a.  Tellina  williamsi  Clark 167 

2.  Exterior  of  left  valve.  Potomac  Creek. 

2a.  Interior  of  same  specimen. 

Fig.  3.  Tellina  vieginiana  Clark  166 

Exterior  of  left  valve.  Hanoverville,  Va. 

Fig.  4.  Mereteix  lenis  (Conrad)  168 

Exterior  of  right  valve.  Woodstock. 

Figs.  5-9.  Mereteix  subimpressa  Conrad  170 

5.  Exterior  of  right  valve.  Acad.  Nat.  Sci.  Phila. 

5a.  Interior  of  same  specimen. 


6.  Dorsal  aspect  of  complete  individnal.  Acad.  Nat.  Sci.  Phila. 

7.  Exterior  of  left  valve.  Same  collection. 

8.  Exterior  of  right  valve. 

8a.  Interior  of  same  specimen. 

9.  Interior  of  left  valve. 

9a.  Exterior  of  same  specimen. 


385 


MARYLAND  GEOLOGICAL  SURVEY. 


eocene,  plate  XXXIIl- 


d 


MOLLUSCA — PELECYPODA. 


TLATE  XXXiV. 

PAGK 

Figs.  1,  la.  Meretiux  ovata  var.  ovata  (Eogers)  168 

1.  Interior  of  right  valve.  West  of  Port  Tobacco,  X 2/7 

la.  Exterior  of  same  specimen. 

Figs.  2-5.  Meeethix  0Vx\ta  var.  pyga  Conrad IGD 


2.  Exterior  of  right  valve. 

2a.  Interior  of  same  sj)ecimen. 

3.  Interior  of  left  valve. 

3a.  Exterior  of  same  si)eeimen. 

4.  Exterior  of  right  valve. 

5.  Exterior  of  left  valve  of  young  individual. 


386 


MARYLAND  GEOLOGICAL  SURVEY 


EOCENE,  PLATE  XXXIV. 


MOLLUSCA PELECYPODA, 


PLATE  XXXV. 

Figs,  la-lg.  Dosmiopsis  lenticularis  (Pogers)  

la.  Interior  of  left  valve.  Glymont. 

lb.  Interior  of  right  valve.  Same  localit3\ 

lc.  Exterior  of  Fig.  la. 

ld.  Exterior  of  Fig.  lb. 

le.  Dorsal  aspect  of  comihete  individnal.  Same  locality. 

lf.  Interior  of  left  valve.  Same  locality. 

lg.  Interior  of  right  valve.  Same  locality. 


PAGE 

171 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXXV. 


MOLLUSCA PELECYPODA. 


PLATE  XXXVI. 

PAGl' 

Fig-s.  1-3.  Pkotocaedia  i.KNis  ('onriid  172 

1.  Exterior  of  right  valve.  1 mile  southeast  of  Mason  Sx^ring’s. 
la.  Interior  of  same  valve. 

2.  Interior  of  left  valve.  Pamnnkey  Iviver,  Va.  Acad.  Nat.  Sci.  Phila. 
2a.  Exterior  of  same  valve. 

3.  Exterior  of  right  valve  from  same  locality  and  in  same  collection. 

Fig-.  4.  Diplodonta  MxVelboeoensis  n.  si) 173 

Exterior  of  left  valve.  Upper  Marlboro.  X 7/4 

Fig’S.  5,  5a,  G,  7.  Diplodonta  hopkinsensis  Clark  174 

5.  Extei-ior  of  left  valve.  Everg-reen,  Va. 

5a.  Interior  of  same  valve. 

6.  Exterior  of  right  valve.  vSame  locality. 

7.  Hinge  much  eitlarged. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXXVI. 


MOLLUSCA PELECYPODA. 


PLATE  XXXVII. 


Eig-s.  1,  la.  Lucina  aquiana  Clark 174 

1.  Exterior  of  right  valve.  Tyj)e  specimen.  Aquia  Creek.  U.  S.  Na- 
tional Museum, 
la.  Interior  of  same  valve. 


Figs.  2,  2a.  Lucusta  astaetiformis  Aldrich  

2.  Interior  of  left  valve.  1 mile  southeast  of  Piscataway. 
2a.  Exterior  of  same  valve. 


Figs.  3,  3a,  3b.  Lucina  dartoni  Clark  

3.  Interior  of  right  valve  of  the  type  specimen.  Woodstock. 
3a.  Exterior  of  same  valve. 

3b.  Exterior  of  left  valve  of  same  individual. 


Figs.  4-7.  Lucina  uhleri  Clark 176 

4.  Exterior  of  right  valve  of  type  specimen.  Woodstock. 

5.  Interior  of  right  valve  of  siiecimen.  1 mile  southeast  of  Mason 

Springs. 

6.  Interior  of  left  valve.  Same  locality. 

7.  Exterior  of  left  valve  of  tyjie  specimen.  Woodstock. 


Figs.  8,  8a,  9.  Lucina  whitei  Clark 176 

8.  Exterior  of  right  valve  of  type  specimen.  Woodstock. 

8a.  Interior  of  same  specimen. 

9.  Exterior  of  left  valve  of  duplicate  type.  Same  locality. 


389 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXXVII. 


. MOLLUSCA PELECYPODA, 


PLATE  XXXVill. 

PAGE 

Figs.  1,  la.  Venekioardia  planicosta  var.  regia  Conrad  ITS 

1.  Exterior  of  right  valve.  Upper  INIarlhoro.  Acad.  Nat.  Sci.  Phila. 

X 9/10 

la.  Interior  of  same  valve. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXXVIII. 


MOLLUSCA PELECYPODA. 


PLATE  XXXIX. 

Fig-s,  1,  la.  Venericardia  planicosta  var.  regia  Conrad  

1.  Exterior  of  left  valve  of  individual  fignired  on  Plate  XXXVIll. 
X 9/10. 

la.  Interior  of  same  valve. 


PAGE 

178 


291 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XXXIX. 


MOLLUSCA — PELECYPODA. 


178 


Figs.  1,  2,  3.  Venericardia  planicosta  var.  regia  Conrad  

1.  Anterior  view  of  complete  individual  figured  on  Plates  XXXVIII 

and  XXXIX.  Acad.  Nat.  Sci.,  Phila. 

2.  Exterior  of  left  valve  of  very  young-  individual. 

3.  Exterior  of  riglit  valve  of  young-  individual. 

Figs.  4-6.  Venericardia  potapacoensis  n.  sp 179 

4.  Exterior  of  left  valve  of  type  specimen.  West  of  Port  Tobacco. 

5.  Exterior  of  left  valve. 

5a.  Interior  of  same  specimen. 

6.  Exterior  of  right  valve. 

6a.  Interior  of  same  specimen. 

Figures  5 and  6 are  from  specimens  in  the  Philadelphia  Acad- 
emy of  Natural  Sciences.  The  locality  of  these  specimens  is  in 
doubt,  but  they  represent  that  form  of  V.  potapacoensis  which 
occurs  typically  in  the  Woodstock  substage. 

Figs.  7,  7a.  Venericardia  marylandica  n.  sp 179 

7.  Exterior  of  right  valve  of  type  specimen.  2y^  miles  above 

Popes  Creek. 

7a.  Interior  of  same  specimen. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XL. 


MOLLUSCA — PELECYPODA, 


PLATE  XLI. 

Eig-s.  1-8.  Ceassatellites  alaeformis  (Conrad)  

1.  Exterior  of  the  right  valve  of  the  type  specimen  of  C.  decUvis 

Heilprin.  Aqnia  Creek.  U.  S.  National  Museum.  (After 
Aldrich.) 

2.  Exterior  of  the  left  valve  of  the  same.  (After  Aldrich.) 

3.  Exterior  of  right  valve.  Fort  Washington. 

3a.  Interior  of  the  same. 

4.  Interior  of  left  valve.  Fort  Washington. 

4a.  Exterior  of  the  same. 

5.  Exterior  of  left  valve. 

6.  Exterior  of  left  valve.  Fort  Washington. 

6a.  Interior  of  the  same. 

7.  Interior  of  left  valve.  Fort  Washington. 

7a.  Exterior  of  the  same. 

8.  Exterior  of  right  valve.  Fort  Washington. 

8a.  Interior  of  the  same. 


PAGE 

180 


393 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XLI. 


MOLLUSCA PELECYPODA. 


PLATE  XLII. 

PAGE 

Figs.  1,  2a,  2b.  Ceassatellites  aquiana  (Clark)  181 

1.  Dorsal  aspect  of  type  specimen.  Aquia  Creek. 

2a.  Exterior  of  left  valve  of  the  same  individual. 

2b.  Exterior  of  right  valve  of  the  same. 

Fig.  3.  Ceassatellites  alta  (Conrad)  18S 

Exterior  of  specimen.  Hardesty. 

Figs.  4,  4a.  Ceassatellites  sp 183 

4.  Exterior  of  right  valve.  Clifton  Beach. 

4a.  Interior  of  the  same. 

Fig.  5.  Astaete  maeylaxdica  Clark  183 

Exterior  of  left  valve  of  type  specimen.  Upper  Marlboro. 


294 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XLII 


MOLLUSCA PELECYPODA 


PLATE  XLIII. 

PAGE 

Fig-s.  1,  la,  2,  2a.  Coralliophaga  (Oryctomya)  bryani  Clark 183 

1.  Exterior  of  right  valve.  1 mile  southeast  of  Mason  Springs, 
la.  Interior  of  the  same  specimen. 

2.  Exterior  of  right  valve  of  the  type  specimen.  Pomonkey 

Neck.  U.  S.  National  Museum. 

2a.  Interior  of  the  same  specimen. 


Fig.  3.  Pholadomya  marylandica  Conrad  184 

Exterior  of  left  valve.  Fort  Washington.  Acad.  Nat.  Sci.  Phila. 

Figs.  4,  5,  5a.  Modiolus  alabamensts  Aldrich  185 


4.  Exterior  of  right  valve.  Mouth  of  Paspotansa  Creek. 

5.  Exterior  of  right  valve.  Potomac  Creek. 

5a.  Exterior  of  left  valve  of  same  individual. 


Fig.  6.  Modiolus  marylandicus  n.  sp 186 

Dorsal  aspect  of  crushed  specimen.  Woodstock. 

Fig.  7.  Litiiopiiaga  marylandica  n.  sp 186 


Exterior  of  left  valve  of  type  specimen.  Clifton  Beach. 


395 


MOLLUSCA PELECYPODA, 


PLATE  XLIV. 

PAGE 

Fig-s.  1,  la.  Anomia  mcgeei  Clark  187 

1.  Exterior  of  left  valve  of  type  siDecimen.  Hanover  Co.,  Va.  Acad. 

Nat.  Sci.  Phila. 
la.  Interior  of  the  same. 

Fig'S.  2,  2a,  3.  Anomia  marylandica  n.  sp 187 

2.  Exterior  of  left  valve.  Pojies  Creek. 

2a.  Interior  of  the  same. 

3.  Exterior  of  left  valve.  Same  locality. 

Fig'S.  4,  5,  6.  Pecten  choctavensis  Aldrich  188 

4.  Exterior  of  rig'ht  valve.  Popes  Creek.  The  height  of  the  orig'- 

inal  is  13.5  mm.  instead  of  11  mm.  as  the  line  indicates. 

5.  Exterior  of  left  valve.  Popes  Creek. 

6.  Exterior  of  left  valve  of  smaller  individual.  Same  locality. 

Figs.  7,  7a,  7b.  Pecten  dalli  Clark  188 

7.  Exterior  of  right  valve  of  type  specimen.  Potomac  Creek. 

7a.  Hinge  of  the  same.  X 2 

7b.  Interior  of  the  same. 

Figs.  8,  8a.  Pecten  johnsoni  Clark  189 

8.  Exterior  of  left  valve  of  type  sjiecimen.  Potomac  Creek. 

8a.  Interior  of  the  same. 

Figs.  9,  9a.  Pecten  sp 190 

9.  Interior  of  right  valve.  Potomac  Creek. 

9a.  Exterior  of  the  same. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XLIV. 


MOLLUSCA PELECYPODA. 


PLATE  XLV. 


PAGE 

OsTKEA  coMPRESsmosTEA  Say  190 

Lower  valve  of  larg-e  individual. 


X % 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XLV. 


MOLLUSCA PELECYPODA, 


PLATE  XLVI. 

PAGE 

Figs.  1,  2.  OsTREA  COMPRESSIROSTRA  Say  190 

1.  Lateral  view  of  specimen  figured  on  Plate  XLV.  X 1 
2a,  2b,  2c.  Exteriors  of  young  lower  valves. 


298 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XLVI. 


MOLLUSCA PELECYPODA, 


PLATE  XLV:i. 

Fig’S.  1-4.  OSTEEA  COMPEESSIROSTRA  Say  

1.  Exterior  of  lower  valve, 

la.  Interior  of  the  same. 

Ih.  Lateral  aspeet  of  the  same  indiviclnal. 

2,  3,  4.  Exteriors  of  young-  upper  valves. 


PAGE 

190 


299 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XLVIl. 


MOLLUSCA PELECYTODA. 


PLATE  XLVIll. 

Figs,  la,  lb.  OsTREA  sellaeformis  Conrad  

la.  Interior  of  lower  valve.  Janies  Eiver,  Va. 

lb.  Exterior  of  upper  valve  of  same  individual  with  lower  valve  i 

position. 


PAGE 

192 


800 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XLVIll. 


MOLLUSCA PELECYPODA, 


PLATE  XLIX. 

Fig-s.  la-ld.  OsTEEA  sellaefoemis  Conrad  

la.  Lateral  view  of  specimen  figured  on  Plate  XL VIII. 

lb,  Ic,  Id.  Exteriors  of  lower  valves  of  young  individuals.  James 

River,  Va. 


PAGE 

192 


301 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  XLIX. 


f 


MOLLUSCA — I'Er.ECYrODA. 


PLATE  L. 

PAGE 

Fig-s.  1-5.  OsTKEA  (Grypiiaeostrea)  vomer  (Mort(Mi)  193 

1.  Exterior  of  lower  valve.  Glymont. 

la.  Lateral  aspect  of  the  same. 

lb.  Interior  of  the  same. 

2,  3.  Exteriors  of  lower  valves  of  yoniig  individnals. 

4.  Exterior  of  iipj)er  valve,  with  typical  form  and  sculpture. 

Upper  Marlboro, 
la.  Interior  of  the  same. 

5.  Exterior  of  lower  valve,  abnormally  elong-ated  and  shallow. 

Clifton  Beach. 

Figs.  6,  6a.  Gryphaea  vesicularis  Lamarck  193 

6.  Exterior  of  lower  valve.  Clifton  Beach. 

6a.  Exterior  of  nj)per  valve  of  same  individual,  with  lower  valve 
in  position. 


302 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  L. 


MOLLUSCA PELECYPODA, 


PLATE  LI. 

PAGE 


Fig-.  1.  Ptekia  limula  (Conrad)  194 

Exterior  of  left  valve.  Popes  Creek. 

Fig-s.  2,  2a,  3,  3a,  4.  Glycymeris  iuoxeus  (Conrad)  194 


2.  Interior  of  s^iecimen.  LTpf>er  klarlboro.  Acad.  Nat.  Sci.  Phila. 

2a.  Exterior  of  the  same  specimen. 

3.  Exterior  of  larg-er  specimen  from  the  same  locality  and  col- 

lection. 

3a.  Interior  of  the  same  specimen. 

4.  Exterior  of  another  specimen  from  Upper  Marlboro. 

Fig'S.  5,  5a.  Trigonoaeca  decisa  (Conrad)  var 195 

5.  Interior  of  a right  valve.  Woodstock. 

5a.  Exterior  of  the  same  valve. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  LI. 


MOLLUSCA PELECYPODA. 


PLATE  LTI. 

PAGE 

Figs,  la,  lb.  CucuLLAEA  gigantea  C'oiirad  . , 196 

la.  Interior  of  left  valve.  I*otoniac  Creek. 

lb.  Exterior  of  same  valve. 


304 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE 


MOLLUSCA PELECYPOUA. 


PLATP]  LTIl. 

Figs,  la,  lb.  CucuLLAEA  gioantea  Conrad  

la.  Interior  of  right  valve  of  individual  figured  on  Plate  Lll. 

lb.  Exterior  of  same  valve. 


PAGE 

196 


305 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  Llll. 


MOLLUSCA PELECYPODA. 


PLATE  LIV. 

'ig-s.  la,  lb,  Ic.  CucuLLAEA  GiGANTEA  Coiirad  

la.  Exterior  of  left  valve  of  young’  of  the  fnut.srerm  ty])e.  Potomac 

Creek. 

lb.  Interior  of  the  same  valve. 

lc.  Dorsal  aspect  of  larg’e  cast.  Fort  Washington. 


PAGE 

19G 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  LIV. 


MOLI.USCA PELECYPODA. 


PLATE  LV. 

PAGE 

Fig-s.  la,  lb,  Ic.  Cucullaea  gtgantea  Conrad  196 

la,  lb.  Diagrams  showing’  transverse  section  of  the  individual 
tig’ured  on  Tdates  Ltl  and  LI II. 

Ic.  Lateral  aspect  of  the  individnnl  figured  on  Plate  LTV,  Fig.  Ic. 


807 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  LV. 


PLATE  LVI. 

PAGH 

Fig'S.  1-4.  Leda  impkoceba  (Conrad)  199 

1.  Exterior  of  right  valve.  Po^Jes  Creek. 

2.  Interior  of  right  valve.  Woodstock. 

3.  Interior  of  right  valve.  Popes  Creek. 

4.  Exterior  of  right  valve.  Popes  Creek. 

Figs.  5,  6,  7,  7a.  Leda  parva  (Kogers)  197 

5.  Dorsal  aspect  of  individual.  Woodstock. 

6.  Exterior  of  right  valve.  Woodstock. 

7.  Interior  of  left  valve.  Woodstock. 

7a.  Exterior  of  same  specimen. 

Figs.  8,  8a.  Leda  cultelliformis  (Rogers)  198 

8.  Exterior  of  right  valve.  Woodstock. 

8a.  Interior  of  right  valve.  Woodstock. 

Figs.  9,  10.  Leda  potomacensis  n.  sp 200 

9.  Exterior  of  right  valve.  Port  Royal,  Va. 

10.  Exterior  of  left  valve  of  young  individual.  Popes  Creek. 

Fig.  11.  Leda  cliftonensis  n.  sp 201 

Exterior  of  right  valve.  2 miles  below  Potomac  Creek. 


308 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  LVI. 


I 


11 


MOLLUSCA PELECYPODA. 


PLATE  LVII. 

PAGE 

Fig-s.  1,  2,  2a.  Leda  parilis  (Conrad)  199 

1.  Exterior  of  left  valve.  Upper  Marlboro. 

2.  Exterior  of  rig'ht  valve.  Same  locality. 

2a.  Interior  of  same  valve. 

Fig.  3.  Leda  parilis  (Conrad)  var 200 

Exterior  of  left  valve.  Probably  from  Woodstock. 

Figs.  4,  4a,  5.  Leda  tysoni  n.  sp.  201 

4.  Interior  of  right  valve.  Woodstock. 

4a.  Exterior  of  same  valve. 

5.  Exterior  of  smaller  right  valve.  Woodstock. 

Fig.  6.  Nucula  ovula  Lea  202 

Exterior  of  left  valve.  Woodstock. 

Figs.  7,  7a,  8,  8a.  Nucula  potomacensis  n.  sp 202 

7.  Interior  of  left  valve.  Woodstock. 

7a.  Exterior  of  same  valve. 

8.  Exterior  of  right  valve.  Woodstock. 

8a.  Interior  of  same  valve. 


309 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  LVIl. 


g 


MOLLUSCA PELECYPODA, 


PLATE  LVIII. 

PAGE 

Figs.  1,  la,  lb,  Ic.  Platidia  makylandica  n.  sjj 203 

1.  Exterior  of  ventral  valve.  Upper  Marlboro. 

la.  Interior  of  the  same. 

lb.  Exterior  of  dorsal  valve  of  the  same  individual. 

lc.  Interior  of  the  same. 

Figs.  2,  3,  3a.  Terebeatula  haelani  Morton 204 

2.  Interior  of  ventral  valve.  3 miles  west  of  Leeland.  X 4/9 

3.  Exterior  of  ventral  valve  from  the  same  locality. 

3a.  Dorsal  asjject  of  the  same  individual. 


310 


MARYLAND  GEOLOGICAL  SURVEY 


I 


EOCENE,  PLATE  LVIll. 


I 


I 


3 


3a 


MOLLUSCOIDEA — BRACHIOPODA. 


PLATE  LIX. 

PAGE 

Figs.  1 and  2.  Fascipora  subramosa  n.  sp 207 

1.  A fragment.  Upper  Marlboro.  X 6 

2.  Surface  of  same,  showing  several  covered  apertures.  X 20 

Fig.  3.  Discosparsa  varians  n.  sp 205 

3.  Surface  of  a parasitic  specimen,  showing*  one  of  its  maculae. 

Uj)i)er  Marlboro.  X 12 

Figs.  4-8.  Cavaria  dumosa  n.  sj) 208 


4.  Portion  of  a small  but  well  j)reserved  branch,  showing  two 

maculae,  prominent  zooecial  mouths,  and  mesopores.  When 
worn  the  walls  are  much  thinner  and  the  apertures  corre- 
spondingly larger.  X 9 

5.  Portion  of  the  fractured  end  of  a branch.  X 20. 

6.  A branch  broken  longitudinally  to  show  the  central  hollow  and 

tubes  bending  outward  from  it.  X 9 

7.  Surface  of  another  specimen,  showing  portion  of  one  of  the  large 

gonocysts  in  right  half  of  figure  and  usual  appearance  of 
zooecia  and  mesof)ores  in  left  half.  It  is  to  be  observed  that 
not  only  the  zooecial  tubes  pass  through  the  gonocyst  but 
smaller  accessory  tubes,  evidently  different  from  the  ordinarj^ 
mesopores,  as  well.  (See  also  Fig.  8.)  X 20 

8.  One  of  the  large  gonocysts  broken  so  as  to  show  the  tubes  i)ass- 

ing  through  it.  X 20 

The  originals  of  Figs.  4-8  are  all  from  Upper  Marlboro. 

Figs.  9-12.  Eeticulipora  dichotoma  Gabb  and  Horn 207 

9.  The  broken  end  (transverse  section)  of  a fragment.  In  the  lower 

half  the  length  of  the  tubes  corresponds  with  the  length  of  the 
branches,  but  in  the  ujiper  part  they  turn  gradually  upward 
until  their  direction  is  nearly  at  right  angles  to  the  length.  X 6 

10.  Upper  and  lower  fourths  of  the  same.  X 20 

11.  I’ortion  of  one  of  the  sides  of  a fragment.  X 20 

12.  A broken  gonocyst  which  was  found  over  a j)revious  smaller 

cyst  which  remains  intact.  X 20 
Figured  specimens  all  from  Upf)er  Marlboro. 

Figs.  13  and  14.  Ceriopora  micropora  Goldfuss  210 

13.  A subglobular  mass,  showing  the  form  usually  characterizing 

this  species.  2%  miles  above  Popes  Creek.  X 6 

14.  Surface  of  the  same.  X 20 

Figs.  15  and  16.  Heteropora  ? tecta  n.  sp 210 

15.  Upper  portion  of  a zoarium.  The  terminal  portions  of  the 

branch  are  covered  uniformly  with  subangular  mouths  of 
tubes,  while  in  the  lower  portion  and  in  the  axis  of  the  main 
bifurcation,  nearly  all  the  mouths  are  covered  with  a finely 
punctate  pellicle.  The  few  apertures  in  the  pelliculate  parts 
are  rounded.  Upper  Marlboro.  X 6 

16.  Portion  of  the  same.  X 20 


Pigs.  17  and  18.  Lepralia  subplana  n.  sp 219 

17.  Surface  of  a specimen  preserving  the  front  wall  of  only  seven 
of  the  zooecia  shown  in  the  figure.  Upper  Marlboro.  X 20 


18.  The  edge  of  a broken  specimen  from  the  same  locality,  showing 
four  layers  of  zooecia.  X 20 


311 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  LIX. 


## 


»?!*•! 


MOLLUSCOIDEA BRYOZOA. 


PLATE  LX. 


PAGE 


Fig'S.  1 and  2.  Membranipora  rimt^lata  n.  sp 211 

1.  Surface  of  a specimen  of  the  small-celled  variety  of  this  species. 

Upper  Marlboro.  X 20 

2.  Surface  of  the  type  specimen.  X 20 

Figs.  3 and  4.  INIembranipora  spiculosa  n.  sp 212 

3.  Surface  of  a siDecimen,  showing  form  and  arrangement  of  zooecia 

and  ovicells.  Upper  Marlboro.  X 20 

4.  Several  zooecia  of  same,  more  hig'hly  magnified. 

Figs.  5 and  0.  JMembranipora  angusta  n.  sp 213 

5.  Surface  of  a specimen,  showing  connecting  pores  and  ovicells. 

Ux3per  Marlboro.  X 25 

6.  Portion  of  another  and  more  worn  specimen,  without  ovicells. 

X 20 

Fig.  7.  Biflustra  torta  Gabb  and  Horn  214 

7.  I’ortion  of  a fragment  of  the  bifoliate  zoarinm  of  this  species. 

Ux)X)er  ]\larlboro.  X 20 

Figs.  8 and  9.  Eeptoflustrella  heteropora  Gabb  and  Horn 213 

8.  Surface  of  the  Eocene  form.  Uj:)x:)er  Marlboro.  X 20 

9.  One  zooecium  of  same  more  highly  magnitied. 

Figs.  10  and  11.  Esch^ra  ??  digitata  Alorton 216 

10.  Surface  of  a fragment  of  the  Eocene  form  of  this  sxDecies.  Upper 

ISlarlboro.  X 20 

11.  Perfect  zooecium  of  same  more  highly  magnified  to  show  the 

lunarium-like  process  of  the  lower  border  of  the  aperture. 

Figs.  12  and  13.  Cribrilina  modesta  n.  sp 218 

12.  Portion  of  the  type  sx3ecimen  of  this  species.  Upper  Marlboro. 

X 20 

13.  One  zooecium  of  same  more  highly  magnitied. 

Fig.  14.  Cribrilina  crassula  n.  sp 218 

14.  Portion  of  the  somewhat  worn  specimen  described.  Upper  Marl- 

boro. X 20 

Figs.  15  and  16.  Lepralia  labiosa  n.  sp 220 

15.  Surface  of  an  average  sx3ecimen.  X 20 

16.  Two  young  zooecia,  each  with  two  avicularia  and  a semilnnate 

area  in  the  upper  xiortion  of  the  apertural  rim.  X 20 

Figs.  17  and  18.  Mucronella  aspera  n.  sp 221 

17.  Surface  of  a sxiecimen.  Upper  Marlboro.  X 20 

18.  A few  zooecia  of  another  specimen.  X 20 

Figs.  19  and  20.  Lunulites  reversa  n.  sp 217 

19.  I’ortion  of  front  surface  of  the  specimen  described.  2 miles 

below  Potomac  Creek.  X 25 

20.  Portion  of  dorsal  surface  of  same.  X 20 


313 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  LX. 


MOLLUSCOIDEA — BRYOZOA. 


PLATE  LXI. 


PAGE 


Fig.  1.  Fragment  of  spatangoid  pi^te 232 

Evergreen,  Va.  X 5/3 

Fig.  2.  Echinoid  spine  232 

Potomac  Creek. 

Figs.  3,  3a.  Flabellum  sp 222 


3.  Upright  view  of  coralhim,  height  12  mm.  1 mile  southeast  of 

I’iscataway. 

3a.  Calicnlar  view,  greater  diameter  of  calice,  15.5  mm. 

Figs.  4,  4a,  4b.  Turbinolia  acuticostata  Vaughan 223 

4.  Upright  view  of  corn  Hum,  height  6.5  mm.  Popes  Creek. 

4a.  Calicular  view,  diameter  of  calice,  3 mm. 

4b.  Margins  of  the  costa*  of  another  specimen  enlarged. 

Figs.  5 to  8.  TROCHOcrATiiiJS  clarkeanus  Vaughan 225 

5.  Uiiright  view  of  a sjiecimen,  height  12.5  mm. 

5a.  Calicular  view  of  the  same,  greater  diameter  of  calice,  7.75  mm. 

6.  Upright  view,  height  10.5  mm. 

7.  Upright  view  of  another  specimen,  height  10  mm. 

8.  Upright  view  of  a fourth  specimen,  height  9.5  mm. 

Figs.  9,  9a,  9b.  Paracyatiius  marylandicus  n.  sp 226 

9.  Upright  view  of  corallum,  height  5 mm.,  1 mile  northeast  of 

Piscataway. 

9a.  Costae  enlarged. 

9b.  Calicular  view,  greater  diameter  of  calice,  5.75  mm. 


Figs.  10,  11.  Balanophyllia  desmophyllitm  M.-E.  and  H 227 

10.  Upright  view,  height  23  mm.,  1 mile  southeast  of  Mason  Springs. 

11.  Uiiright  view  of  another  specimen,  height  26  mm.  Same  locality. 

Figs.  12  to  14.  Eupsammta  elaborata  (Conrad)  229 


12,  Upright  view  of  a specimen,  height  17.5  mm. 

13,  13a.  Conrad’s  type  (from  Alabama),  length  of  corallum,  13  mm.: 

greater  diameter  of  calice,  12  mm. 

14,  14a.  An  unusually  slender  specimen;  height  of  corallum,  15.5 

mm.;  greater  diameter  of  calice,  9.5  mm.  Potomac  Creek. 

Figs.  15,  15a,  15b.  Eupsammia  conradi  Vaughan 231 

Conrad’s  type  of  TnrhhioUa  pilcolus  (not  Turhinolia  pileolus  Eich- 
wald).  Height  of  corallum,  11  mm.:  greater  diameter  of  calice, 

13  mm.  Acad.  Nat.  Sci.  Phila. 


MARYLAND  GEOLOGICAL  SURVEY. 


EOCENE,  PLATE  LXI. 


ECIIINODERMATA  AND  COELENTERATA. 


T’LATE  LXTT. 


PAGE 

Fig-.  1.  Textularta  gramen  d'Orbigny  233 

1 mile  nortlieast  of  Piscataway.  X 50 

Fig.  2.  Textularta  sagittela  Def ranee  234 

Upper  Marlboro.  X 50 

Fig.  3.  Textularia  surangueata  d’Orbigny  234 

Brooks  Estate  near  Seat  Pleasant.  X 50 

Fig.  4.  Spiroplecta  clarki  Bagg  235 

Type  specimen.  Woodstock.  X 50 

Fig.  5.  XODOSARIA  AFFTXIS  (d’Orbigny)  236 

Woodstock.  X 10 

Fig.  G.  Nodosaria  bacillum  Defrance  236 

3 miles  west  of  Leeland.  X 10 

Fig.  7.  Nodosaria  communis  (d’Orbigny)  237 

1 miles  northeast  of  Piscataway.  X 21 

Fig.  8.  Nodosaria  consorbrina  var.  emagiata  (Benss)  238 

Upper  Marlboro.  X 10 

Fig.  9.  Nodosaria  sandbergeri  (Eenss)  238 

Upper  Marlboro.  X 24 

Fig.  10.  Nodosaria  obeiqua  (Linne)  239 

Upjier  Marlboro.  X 10 


3U 


PROTOZOA FORAMINIFERA. 


PLATE  LXIII. 

PAGE 

Fig.  1,  Vaginulina  legumex  (Linne)  240 

Prooks  Estate  near  Seat  ITeasant.  X 50 

Figs.  2,  3.  ]\1abginulina  costata  (Batsch)  240 

2.  Large  individual  from  Ujjper  Marlboro.  X 24 

3.  Smaller  individnal  from  same  locality.  X 50 

Fig.  4.  CniSTELLARiA  GiBBA  d’Orbigiiv  241 

1 mile  northeast  of  Piseataway.  X 24 

Fig.  5.  CniSTELLABiA  ROTATUEA  (Laimirck)  242 

1 mile  southeast  of  Mason  Springs.  X 7 

Fig.  6.  Crtstellabia  radiata  (Bornemann)  243 

Woodstock.  X 24 

Fig.  7.  PoLYMORPinxA  AUSTRIACA  (d’Orbigiiy)  244 

Woodstock.  X 50 

Figs.  8,  9.  PoLYMORPiiiNA  COMMUNIS  (d’Orbigny)  244 

8.  Woodstock.  X 50 

9.  Upper  Marlboro.  X 50 

Fig.  10.  POLYMORPIIINA  c OMPRESSA  d’  Orbigiiy  240 

Woodstock.  X 40 

Fig.  11.  POLYMORPIIINA  ELEGAN^i  issiMA  Parker  and  Jones 247 

Woodstock.  X 50 

Fig.  12.  POLYMORPIIINA  GIBBA  (d’Orbigny)  248 

Brooks  Estate  near  Seat  ITeasant.  X 50 

Fig.  13,  POLYMORPIIINA  LACTEA  (Walker  and  Jacob)  248 

Upper  ?^IaiTboro.  X 50 

Pig,  14.  POLYMORPIIINA  PRAELONGA  Tcrcpiem  249 

Woodstock.  X 32 

Figs.  15,  16,  IGa.  Globigerina  bulloides  d’Orbigny 250 

Well  at  Chesapeake  Beach  at  90-92  feet.  X 50 


315 


PROTOZOA FORAMINIFERA. 


PLATE  LXIV. 

Fig.  1.  Discoebina  bertheloti  (cFOrbigny)  

Woodstock.  X 62 

Fig.  2.  Discoebina  turbo  (d’Orbigny)  

Upper  Marlboro.  X 62 

Fig.  3.  Truncatulina  lobatula  (Walker  and  Jacob)  

Upper  Marlboro.  X 62 

Fig.  4.  Truncatulina  ungeriana  (d'Orbigny)  

Upper  Marlboro.  X 30 

Fig.  5.  Anomalina  ammonoides  (Eeuss)  

Upj)er  Marlboro.  X 62 

Fig.  6.  Anomalina  geosserugosa  (Giimbel)  

1 mile  northeast  of  Piscataway.  X 62 

Fig.  7.  PULVINULINA  EXIGNA  Var.  OBTUSA  BniTows  

1 mile  northeast  of  Piscataway.  X 62 

Fig.  8.  PULVINULINA  sciiREiBERSii  (d’Orbigny)  

Woodstock.  X 62 

Fig.  9.  Nonionina  aefinis  Reuss  

Woodstock.  X 62 

Fig.  10.  Ampiiistegina  lessonii  d’Orbigny  

Woodstock.  X 25 

Figs.  11,  11a,  11b.  Carpolithus  marylandicus  n.  sp 

11.  Longitudinal  section,  showing  position  and  shape  of  seed  cell. 

Popes  Creek. 

lla.  Entire  fruit,  side  view. 

llb.  Entire  fruit,  viewed  at  the  apex. 

Figs.  12,  12a,  12b.  Carpolithus  marylandicus  var.  rugosus  n.  var 

12.  Longitudinal  section,  showing  position  and  shaxie  of  seed  cell. 

Pojies  Creek. 

12a.  Entire  fruit,  side  view. 

12b.  Entire  fruit,  viewed  at  the  apex. 


PAGE 

251 

251 

252 

253 

251 

254 

255 

256 

257 

257 

258 

258 


316 


PROTOZOA— FORAMINIFER,  AND  PLANTAE. 


INDEX 


A.  C. 


Academy  of  Natural  Sciences,  Phila- 
delphia, 17. 

Accumulation  of  deposits,  conditions 
of,  90. 

Alabama,  Claiborne  beds  of,  27. 

Aldrich,  T.  H.,  31,  75,  77,  79. 

“ Alluvial  deposits,”  25. 

Alluvial  formation,  25. 

Annapolis,  fossils  from,  74,  76,  78,  80, 
149,  178,  205. 

Appalachian  Kegion,  21. 

Aquia  Creek,  section  near,  68,  69. 

Aquia  Creek,  fossils  from,  74,  76,  78, 
80,  96,  98,  102,  104,  105,  107,  124,  133.^ 
132,  138,  146,  148,  149,  151-154,  160- 
162,  166,  172-174,  178,  181,  182,  186, 
192,  193,  197,  201,  223,  225,  231. 

Aquia  formation,  58,  85. 

Aquia  formation,  composition  of,  59. 

Aquia  formation,  distribution  of,  74, 
80. 

Aquia  formation,  description  of,  59. 

Aquia  formation,  fossils  from,  58,  68, 
69,  71,  72,  73,  74,  76,  78,  80. 

Aquia  formation,  relation  of  to 
Chickasawan,  87. 

Aquia  stage,  species  of,  86,  87. 

Arundel  formation,  45. 

Ashley,  S.  C.,  101. 

Atlantic  Coast  Province,  distribution 
of  Eocene  in,  75. 

B. 

Bagg,  E.  M.,  Jr.,  16,  31,  93. 

Bailey,  J.  W.,  31,  56. 

Bassler,  Eay  S.,  31,  41,  121. 

Bells  Landing  substage,  37,  84. 

Bibbins,  A.,  30. 

Bognor  rock,  92. 

Booth,  I.  C.,  28,  32,. 

Bracheux  sands,  37,  92. 

Broad  Creek,  section  near,  73. 

Buhrstone,  37. 

Buena  Vista,  fossils  from,  74,  76,  78, 
80,  138. 
h 


Case,  E.  C.,  16,  93. 

Calcaire  Grossier,  91. 

Chapel  Point,  fossils  from,  75,  77,  79, 
81,  145,  152,  160,  164,  166,  169,  177, 
179,  193,  201. 

Character  of  Eocene  deposits,  52. 

Charles  Branch,  fossils  from,  75,  77, 
79,  81,  201,  203. 

Charles  County,  102. 

Chesapeake  Beach,  fossils  from  well 
at,  75,  77,  79,  81,  160,  161,  166,  247, 
251,  254,  256. 

Chesapeake  group,  47. 

Chester  Eiver,  section  on,  73. 

ChickasaAvan  stage,  84,  87,  89. 

City  Point,  Va.,  33,  34. 

Claiborne  beds  of  Alabama,  27. 

Claibornian  stage,  84. 

Clark,  Wm.  Bullock,  9,  21,  32,  93. 

Cleaveland,  Parker,  25,  33. 

Clifton,  fossils  from,  74,  76,  80,  95-97, 
100,  112,  123,  125,  138,  148,  149,  151, 
152,  160-164,  166,  170,  172,  176,  181, 
183,  185-187,  191,  194,  197,  198,  201. 

Coastal  Plain,  21. 

Coastal  Plain  deposits,  general  rela- 
tions of,  44. 

Collington,  fossils  from,  74,  76,  78,  80, 
149,  170,  178,  181. 

Columbia  formation,  49. 

Commission,  5. 

Conditions  of  accumulation  of  Eo- 
cene deposits,  90. 

Conrad,  T.  A.,  27,  28,  29,  33,  34,  35,  51, 
91. 

Contents,  11. 

Cope,  E.  D.,  111. 

Correlation  of  deposits,  82. 

Correlation  of  deposits  with  those  of 
Europe,  91. 

Cretaceous,  75,  77,  79,  81. 

Cretaceous,  description  of,  45. 

Crownsville,  fossils  from,  74,  76,  78,  80, 
138. 


318 


INDEX 


D. 

Dali,  W.  H.,  17,  35,  83,  92,  166,  167,  197. 
Dana,  James  D.,  35. 

Darton,  N.  H.,  30,  35,  40,  49,  57. 
Delaware,  Eocene  of,  49. 

Depth  of  sedimentation,  57. 
Distribution  of  species  in  Aquia  for- 
mation, 74,  76,  78,  80. 

Distribution  of  species  in  Eocene,  75, 

77,  79,  81. 

Distribution  of  species  in  Xanjemoy 
formation,  75,  77,  79,  81. 
Distribution  of  species,  73. 

Distribution  of  strata,  49. 

Diicatel,  J.  T.,  28,  36. 

E. 

Eastman,  Charles  E.,  16,  93. 

Ehrenberg,  C.  G.,  56. 

Eocene  deposits,  comiDosition  of,  52. 
Eocene  deposits  correlated  within 
Middle  Atlantic  Slope,  82. 

Eocene  deposits,  general  character 
of,  23,  52. 

Eocene  deposits,  general  distribution 
of,  75. 

Eocene  deposits,  origin  of,  54. 

Eocene  deposits,  strike  and  dip  of,  53. 
Eocene  deposits,  thickness  of,  54,  90. 
Eocene  foraminifera,  31. 

Eocene  formations  correlated  with 
Gulf  states,  83. 

Eocene,  first  use  in  America,  27. 
Eocene  of  Middle  Atlantic  Slope,  de- 
scription of,  46. 

Eocene  strata,  distribution  of,  49. 
Eolignitic,  37. 

European  equivalents,  91. 

Evergreen,  Va.,  fossils  from,  174,  232. 

F. 

Faunal  stages,  table  showing,  58. 
Featherstonhaugh,  G.  W.,  36. 

Finch,  John,  25,  36. 

Fireman,  Peter,  analyses  by,  53. 
Fontaine,  W.  M.,  36. 

Formations,  table  showing,  58. 
Formations  and  faunal  stages,  58. 
Fort  Washington,  27,  31*  33. 

Fort  Washington,  fossils  from,  74,  76, 

78,  80,  104-106,  138,  148,  149,  151, 
152,  161,  162,  166,  167,  170,  172,  179, 
181,  185,  186,  191,  192,  197. 


Fossils  of  Paspotansa  substage,  63. 
Fossils  of  Piscataway  substage,  61. 
Fossils  of  Potapaco  substage,  65. 
Fossils  of  Woodstock  substage,  66. 
Fredericktown,  fossils  from,  74,  76,  78, 
80,  172,  178,  193,  197. 

G. 

General  stratigraphic  relations,  44. 
Geographical  distribution  of  species, 
73. 

Geological  criteria,  89. 

Geological  distribution  of  species,  73. 
Geological  divisions,  15. 

Gilman,  Daniel  C.,  5. 

Glymont,  61. 

Glymont,  fossils  from,  74,  76,  78,  80, 
107,  148,  149,  151,  152,  162,  163,  165, 
170,  172,  176,  181,  182,  186,  191,  193, 
197. 

Glymont,  section  at,  68. 

Greensand,  origin  of,  55. 

Greggs  Landing  substage,  84. 
Grimesville,  fossils  from,  74,  76,  78,  80, 
170,  172,  192. 

Gulf  province,  distribution  in,  75. 

H. 

Hanover  county,  Va.,  fossils  from,  188. 
Hardesty,  fossils  from,  74,  76,  78,  80. 
141,  148,  151,  162,  170,  172,  178,  182, 
191,  195,  197. 

Harris,  G.  D.,  17,  30,  37,  75,  77,  79,  133, 
166,  167,  197. 

Harrisons  Landing,  fossils  from,  74, 
76,  78,  80,  172. 

Hatchetigbee  substage,  84. 

Hayden,  H.  H.,  25,  37. 

Heilprin,  A.,  37,  91. 

Heinrich,  O.  J.,  38. 

Hering,  Joshua  W.,  5. 

Higgins,  James,  30,  38. 

Hilgard,  E.  W.,  48. 

Hills  Bridge,  fossils  from,  75,  77,  79, 
81,  160,  165,  194. 

Historical  review,  24. 

Hollick,  Arthur,  16,  93. 

Hotchkiss,  Jed.,  38. 

Hunter,  H.  C.,  17. 

I. 

Illustrations,  List  of,  13. 

Introduction,  21. 

Iterson,  F.  von,  17. 


INDEX 


319 


J. 

Jacksonian,  fossils  from,  75,  77,  79,  81. 
Jacksonian  stage,  84,  85. 

Jaekel,  O.,  104. 

James  river,  deposits  of,  29. 

Johns  Hopkins  University,  collections 
of,  17. 

Johnson,  C.  W.,  17. 

K. 

Kalm,  Peter,  24,  38. 

Ivoken,  E.,  114,  115. 

L. 

Lafayette  formation,  47. 

La  Plata,  fossils  from,  75,  77,  79,  81, 
180. 

Lea,  Henry  C.,  39. 

Lea,  Isaac,  27,  39,  91. 

Leeland,  fossils  from,  74,  76,  78,  80, 
181,  191,  197,  205,  237. 

Leidy,  Joseph,  101. 

Letter  of  transmittal,  9. 

Lignitic  of  Gulf,  37. 

Liverpool  Point,  fossils  from,  74,  76, 
78,  80,  95,  300,  103,  104,  105-107,  132, 
136,  148,  149,  151,  3 52,  160,  164,  170, 
172,  176,  181,  182,  185,  192,  197,  201. 
London  clay,  27,  33,  91. 

LovN'er  Chickasawan  stage,  85. 

Lower  Chickasawan  stage,  fossils 
from,  75,  77,  79,  81. 

Lower  Claibornian,  85. 

Lyell,  Chas.,  29,  39,  91. 

Lyons  Creek,  section  near,  72. 

M. 

McConnell,  J.  C.,  17. 

McGee,  W J,  30,  40,  49. 

Maclure,  William,  24,  39. 

Manasquan  formation,  205. 

Marlboro  clay,  65. 

Marlboro  Point,  fossils  from,  226,  233. 
Marls,  analyses  of,  53. 

Marsh,  O.  C.,  111. 

Marshall  Hall,  162. 

Martin,  George  Curtis,  21,  93. 
Maryland,  Eocene  in,  50. 

Mason  Springs,  fossils  from,  74,  76,  78, 
80,  125-127,  129-131,  140,  144,  146, 
148,  149,  151-153,  155,  161-163,  166, 
170,  173,  176,  181,  184,  186,  191,  197, 
229,  231,  237,  243. 


Matawan  formation,  45. 

Mattawoman  Creek,  fossils  from,  74, 
76,  78,  80,  106,  172,  176,  181,  182,  191. 
Maury,  M.  F.,  39. 

Meyer,  O.,  91. 

Middle  Atlantic  Slope,  21. 

Midwayan  stage,  84,  85. 

Miller,  S.  A.,  40. 

Monmouth  formations,  45. 

Morton,  S.  G.,  26,  27,  40. 

Mount  Misery,  deposits  at,  52. 

Mullica  Hill,  N.  J.,  214,  215,  216. 
Murchison,  K.  I.,  29,  41. 

Murray  & Renard,  55. 

N. 

Xanafalia  substage,  84. 

Xanjemoy  Creek,  66. 

Xanjemoy  Creek,  fossils  from,  75,  77, 
79,  80,  125,  145,  160,  164,  165,  169, 
179,  199,  203. 

Xanjemoy  Creek,  section  near,  70. 
Xanjemoy  formation,  47,  58,  69,  70,  71, 
72,  85. 

Xanjemo}"  formation  described,  64. 
Xanjemoy  formation,  relations  to 
Chickasawan,  89. 

X'anjemoy  stage,  species  of,  87,  88. 
Xeocene  deposits  described,  47. 

Xew  Jersey,  greensands  of,  28. 
Xickles,  John  M.,  31,  41. 

Xoetling,  F.,  104. 

O. 

Origin  of  Eocene  materials,  54. 

Ostrea  sellaeformis  zone,  83. 

Oxen,  section  at,  71. 

P. 

Paleontological  criteria,  84. 

Pamunkey  formation,  35,  57. 
Pamunkey  Group,  58. 

Pamunkey  river,  Ya.,  35. 

Pamunkey  river,  Va.,  fossils  from,  232. 
Paspotansa  Creek,  fossils  from,  74,  76, 
78,  80,  141,  147,  149,  151,  155,  162, 
170,  173,  178,  181,  186,  189,  191.  197. 
Paspotansa  stage,  58,  69,  72,  73,  71,  75, 
76,  77,  78,  79,  80,  81. 

Paspotansa  stage  described.  62. 
Paspotansa  stage,  distribution,  74,  80. 
Paspotansa  stage,  fossils  of,  63. 
Patapsco  formations,  45. 


320 


INDEX 


Patuxent  formations,  45. 

Patuxent  river,  section  on,  73. 

Piedmont  Plateau,  21. 

Pierce,  James,  26,^41. 

Pilsbry,  H.  A.,  17. 

Pisgah,  fossils  from,  74,  76,  78,  80,  172, 
191. 

Piscataway,  33,  34. 

Piscataway,  fossils  from,  75,  77,  79,  81, 
124,  125,  126,  128,  131,  133,  135,  136, 
147-149,  151,  157,  159-165,  169,  171- 
173,  175,  176,  178,  180,  181,  185,  188, 
191,  193,  195,  197,  201,  202,  223,  226, 
227,  233,  242,  255,  256. 

Piscataway,  section  at,  72. 

Piscataway  Creek,  fossils  from,  74,  76, 
78,  80,  150. 

Piscataway  stag-e,  58,  68,  69,  71,  73,  74, 
75,  76,  77,  78,  79,  80,  81. 

Piscataway  stage  described,  60. 

Piscataway  stage,  distribution  in,  74, 
80. 

Piscataway  stage,  fossils  of,  61. 

Pleistocene  deposits  described,  48. 

Pomonkey  Neck,  fossils  from,  74,  76, 
78,  80,  132,  133,  143,  184. 

Popes  Creek,  fossils  from,  75,  77,  79, 
81,  102,  106,  108,  115,  123,  128,  130, 
131,  136,  138,  139,  142,  146,  149,  150, 

152,  155,  159,  161,  163-166,  169,  171, 

173,  175,  176,  177,  179,  180,  182,  185, 

187,  188,  192,  194,  195,  197,  198,  199, 

202,  203,  210,  225. 

Popes  Creek,  section  near,  70,  71. 

Post  Eocene,  fossils  from,  75,  77,  79, 
81. 

Port  Tobacco,  32,  66. 

Port  Tobacco,  fossils  from,  75,  77,  79, 
81,  115;  124,  125,  131,  145,  151,  152, 
159,  160,  179,  193,  201. 

Potapaco  stage,  58,  65,  69,  70,  72,  75, 
77,  79,  81. 

Potapaco  stage  described,  65. 

Potapaco  stage,  distribution  in,  75. 

Potapaco  stage,  fossils  of,  65. 

Potomac  Creek,  75. 

Potomac  Creek,  fossils  from,  74,  75-80, 
100,  124-126,  129,  131-134,  136,  137, 
140,  141,  144,  146-148,  150-157,  162, 
163,  166,  170,  172,  173,  176,  178-182, 
186,  189-191,  193,  195,  197,  201,  218, 
225,  226,  231,  232,  237. 

Potomac  Creek,  section  near,  69,  70. 

Potomac  Groui),  45. 


Potomac  Elver  section,  67. 

Potomac  river,  section  on,  67. 

Preface,  15. 

Probst,  J.,  104. 

R. 

Eancocas  formation,  45. 

Earitan  formation,  45. 

Eeedy  Eun,  fossils  from,  74,  76,  78,  80,. 

170,  172,  182,  191. 

Eogers,  H.  D.,  28,  42. 

Eogers,  William  B.,  27,  28,  41,  42,  51. 
Eolph’s  Landing,  fossils  from,  74,  76, 
78,  80,  148,  150,  162,  173,  178,  181, 
195,  197. 

Eolph’s  Landing,  sections  near,  73. 
Euffin,  Edmund,  42. 

S. 

Say,  Thomas,  26,  42. 

Schuchert,  Charles,  16,  204. 

Schopf,  Johann  David,  24,  42. 

Seat  Pleasant,  fossils  from,  74,  76,  78, 
80,  120,  148,  149,  162,  170,  172,  181- 
183,  192,  235,  238,  240,  254. 

Seat  Pleasant,  section  near,  71. 
Secondary  formation,  25. 

Section  at  Glymont,  68. 

Section  near  Lyons  Creek,  72. 

Sections  near  Potomac  Creek,  69-70. 
Section  of  Potomac  river,  67,  68. 
Section  of  western  portion  of  bluif  at 
Aquia  Creek,  69. 

Sedimentation,  depth  of,  57. 

Severn  river,  fossils  from,  74,  76,  78,. 

80,  179,  191,  232. 

Severn  river,  section  near,  13. 

Shark  Eiver  formation,  205. 

Shattuck,  G.  B.,  30,  49. 

Silvester,  E.  W.,  5. 

Smith,  John  Walter,  5. 

Southeast  Creek,  fossils  from,  74,  76,. 
78,  80,  188,  189. 

South  Eiver,  fossils  from  near,  74,  76,. 
78,  80,  145,  148-150,  172,  173,  178, 
179,  181,  183,  191-193,  195,  197,  200,. 
202,  232. 

South  Eiver,  section  at,  73. 

Species,  distribution  of,  73. 
Stratigraphical  and  paleontological 
characteristics,  57. 

Strike  and  dip  of  Eocene  deposits,  53. 
Suessonian,  92. 

Swan  Creek,  fossils  from,  74,  76,  78,  80, 
191. 


INDEX 


321 


T. 

Table  of  correlation,  85. 

Table  showing-  formations  and  faunal 
stages,  58. 

Table  showing  geographical  and  geo- 
logical distribution  of  species,  73. 

Table  showing  local  and  general  dis- 
tribution of  Eocene  species,  74. 

Timber  Creek,  N.  J.,  208,  214,215,216,219. 

Tertiary  formations,  22,  25. 

Thanet  sands,  37,  92. 

Thickness  of  Eocene  deposits,  54. 

Thrift,  fossils  from,  75,  77,  79,  81,  168, 
197. 

Thrift,  section  near,  72. 

Tinkers  Creek,  fossils  from,  74,  76,  78, 
80,  148,  149,  162,  191. 

Transgression  of  Eocene  deposits,  83. 

Transmittal,  letter  of,  9. 

Tuomey,  M.,  43,  123. 

Turritella  rock,  64. 

Tyson,  Philip  T.,  30,  43. 

U. 

Uhler,  P.  R.,  30,  43. 

Ulrich,  E.  O.,  16,  81,  93. 

U.  S.  Geological  Survey,  17. 

U.  S.  National  Museum,  17. 

Upper  Chickasawan,  85. 

Upper  Chickasawan,  fossils  from,  75, 
77,  79,  81. 

Upper  Claibornian,  85. 

Upper  Marlboro,  31,  32,  34. 

Upper  Marlboro,  fossils  from,  74-81, 
117,  118,  120,  121,  124,  136,  140,  143, 
145,  148-152,  155,  157-162,  164,  165, 
169-176,  178,  180,  181,  183,  186,  188, 
189,  191-195,  197,  199,  200,  202,  203, 
206-208,  210-216,  218-222,  231-234, 

237-239,  241-243,  249,  252-254. 

Upper  Marlboro,  section  near,  72. 


V. 

Van  Rensselaer,  J.  26,  43. 

Vannxem,  Lardner,  26. 

Vaughan,  T.  Wayland,  16,  43,  81,  93. 

Vincentown,  N.  J.,  121,  206,  208,  209, 
212,  214,  215,  216,  220,  222. 

Virginia,  Eocene  of,  51. 

W. 

Wades  Bay,  fossils  from,  74,  76,  78,  80, 
181,  186,  191. 

Washington,  D.  C.,  35. 

Washington,  fossils  from  near,  163. 

Willis,  Bailey,  40. 

Williams,  G.  H.,  40. 

Winchester,  fossils  from,  74,  76,  78,  80, 
162. 

Woods  Blnlf,  Ala.,  227 

Woods  Blulf  substage,  84,  223. 

Woodstock,  fossils  from,  75,  77,  79,  81, 
100,  105,  106,  109,  115,  122,  124,  125, 
131,  133,  135,  136,  143,  150-152,  160, 
163-166,  168,  171,  173,  175-177,  179, 
184-187,  189,  192,  195-199,  201-203, 
223,  236,  237,  243,  244,  246,  247,  249, 
251,  253,  256-258. 

Woodstock,  section  at,  70. 

Woodstock  stage,  58,  66,  70,  71,  75,  77, 
79,  81. 

Woodstock  stage  described,  66. 

Woodstock  stage,  distribution  of  spe- 
cies from,  75,  77,  79,  81. 

Woodstock  stage,  fossils  of,  66. 

Woodstock,  Va.,  31. 

Woodward,  A.  S.,  98,  101. 

Woodward,  Smith,  104. 

Wyman,  Jeffries,  111,  112,  115. 


PALEONTOLOGICAL  INDEX 


A. 

Actaeonidae,  123. 

Actinopterygii,  110. 

Acteon  metanellus,  156. 

Aetobatis,  101. 

Aetobatis  arcuatus,  74,  75,  102,  265. 
Aetobatis  profundus,  102. 
Amphistegina  lessonii,  67,  80,  81,  257, 
316. 

Angelas,  166. 

Anomalina  ammonoides,  63,  80,  81,  255, 
316. 

Anomalina  grosserugosa,  63,  80,  81, 
25//,  316. 

Anomalodesmacea,  184. 

Anomia  marylandica,  78,  79,  187,  295. 
Anomia  mcg’eei,  187,  295. 

Anomia  rufdni,  187. 

Anomiidae,  187. 

Anthozoa,  222. 

Aporrhaidae,  146. 

Aporrhais  potomacensis,  63,  76,  77, 
U6,  277. 

Area  onochela,  196. 

Area  rogersi,  196. 

Areidae,  194. 

Artemis  lentieularis,  171. 

Arthropoda,  74,  75,  116. 
Aspidobranehiata,  157. 

Astarte  marylandiea,  63,  72,  78,  79, 
183,  294. 

Astartidae,  183. 

Asterospondyli,  102. 

Athleta  tuomeyi,  130. 

Avieula  limula,  194. 

B. 

Bairdiidae,  116. 

Balanophyllia  desmophyllum,  63,  80, 
81,  85,  86,  227,  313. 

Berenieea,  206,  208. 

Bierisina  gaudryana,  207,  208. 

Biflustra  disjuneta,  212. 

Biflustra  torta,  63,  80,  81,  2Z//,  312. 
Braehiopoda,  78,  79,  203. 


Bryozoa,  78,  79,  80,  81,  205. 

Bueeinidae,  3 36. 

Bj^ssomya  petrieoloides,  186. 
B3^thoeypris  j)arilis,  63,  74,  75,  117,  268. 
Bythoeypris  subaequata,  63,  74,  116, 
117,  268. 

C. 

Cadulus  abruptus,  59,  66,  76,  77,  85,  86, 
87,  88,  89,  159,  281. 

Cadulus  bellulus,  159. 

Cadulus  subeoaretatus,  160. 
Calliostoma  sp.,  63,  76,  77,  157. 
Calyptraea  aperta,  59,  76,  77,  85,  86,  88, 
89,  152,  280. 

Calj^ptraea  aperta,  152. 

Calyptraea  troehiformis,  152. 
Calj^ptraphorus  jaeksoni,  63,  72,  76,  77, 
"755,  277. 

Calj'ptraphorus  trinodiferus,  59,  65, 
76,  77,  85,  86,  88,  lJf5,  277. 
Cal^'ptraphorus  trinodiferus  (?)  var., 
"76,  74,  11,6. 

Calj^ptraphorus  velatus,  146. 
CaB^ptrophorus.  See  Calyptraphorus. 
Caneellaria  graeiloides,  128. 
Caneellaria  graeiloides  var.,  63,  74,  75, 
85,  86,  128,  273. 

Caneellaria  (Narona)  potomaeensis, 
63,  74,  75,  129,  273. 

Caneellaria  parva,  129. 

Caneellaria  ulmula,  129. 

Caneellaria  sp.,  63,  74,  75,  129,  273. 
Caneellaridae,  128. 

Caneroidea,  116. 

Capulidae,  152. 

Careharias,  109. 

Carehariidae,  108. 

Careharodon,  107. 

Careharodon  aeutidens,  108. 
Careharodon  angustidens,  108. 
Careharodon  aurieulatus,  66,  74,  108. 
Careharodon  eontortidens,  108. 
Careharodon  erassidens,  108. 
Careharodon  reetus,  108. 


324 


PALEONTOLOGICAL  INDEX 


Cardiidae,  172. 

Cardita  planicosta,  178, 

Carditidae,  172,  177. 

Cardium  (Protocardia)  lenis,  172,  173. 
Cardium  nicolletti,  172. 

Caricella  pyruloides  (?),  60,  74,  75,  85, 
86,  ISl,  273. 

Caricella,  131. 

Caricella  sp.,  62,  131. 

Carpolithus  marylandicus,  67,  80,  81, 
258,  316. 

Carpolithus  marylandicus  var.  I'ug'o- 
sus,  67,  80,  81,  258,  316. 
Caryophyllidae,  225. 

Cassididae,  144. 

Cassidaria  brevidentata,  144. 

Cavaria  dumosa,  63,  78,  79,  208,  311. 
Cavaria  ramosa,  209. 

Cephalopoda,  74,  75,  122. 

Ceriopora  micropora,  65,  80,  81,  210, 
311. 

Cerioporidae,  208. 

Cestraciontidae,  102. 

Cheloniidae,  97, 

Chilostomata,  211. 

Chrysodomus  engonatus,  63,  76,  77,  85, 

86,  IJ/O,  274. 

Cidaridae,  232. 

Cidaroida,  232. 

Cl3^donautilidae,  122. 

Coelenterata,  80,  81,  222. 
Compressidens,  159. 

Coprolites,  96,  115,  262. 

Coralliophaga  bryani,  63,  78,  79,  183. 
Coralliophaga  (Oryctomya)  bryani, 

183,  295. 

Corbula  alabamiensis,  163. 

Corbula  aldrichi,  76,  77,  85,  86,  88,  163, 
284. 

Corbula  nasuta,  163. 

Corbula  oniscus,  59,  67,  70,  76,  77,  85, 

87,  88,  89,  164,  284. 

Corbula  (Aloidis)  oniscus,  164. 

Corbula  sp.,  71. 

Corbulidae,  163. 

Corbula  subengonata,  59,  67,  71,  76,  77, 
85,  86,  87,  163,  284. 

Crassatella  alaeformis,  180. 

Crassatella  alta,  182. 

Crassatella  capri-cranium,  180. 
Crassatella  declivis,  180. 

Crassatella  palmula,  180. 

Crassatella  protexta,  180. 


Crassatellites  alaeformis,  60,  61,  64,  68, 
69,  71,  72,  73,  78,  79,  180,  182,  183, 
293. 

Crassatellites  alta,  63,  78,  79,  182,  294. 
Crassatellites  aquiana,  60,  61,  78,  79, 
181,  294. 

Crassatellites  palmula,  181. 
Crassatellites  sp.,  78,  79,  183,  294. 
Crassatellitidae,  180. 

Cribrilina  crassula,  63,  80,  81,  218,  312. 
Cribrilina  modesta,  63,  80,  81,  218,  312. 
Cribrilinidae,  218. 

Cristellaria  acutauricularis,  241. 
Cristellaria  crepidula,  242. 

Cristellaria  cultrata,  243. 

Cristellaria  excisa,  241. 

Cristellaria  gibba,  63,  80,  81,  241,  315. 
Cristellaria  pulchella,  241. 

Cristellaria  radiata,  66,  80,  81,  243,  315. 
Cristellaria  rotulata,  63,  80,  81,  242, 
315. 

Cristellariae,  240. 

Crocodilia,  95. 

Crocodilidae,  95. 

Crustacea,  116. 

Cryptodira,  97. 

Cucullaea  gigantea,  59,  61,  64,  69,  71, 
72,  73,  78,  79,  85,  86,  87,  88,  196,  304, 
305,  306,  307. 

Cucullaea  gigantea  var.,  196. 

Cucullaea  onochela,  196. 

Cucullaea  rogersiana,  196. 

Cucullaea  transversa,  196,  197. 
Cyclostomata,  205. 

Cylichna  aldrichi,  125. 

Cylichna  venusta,  59,  70,  74,  75,  124, 
271. 

Cypraea  smithii,  65,  76,  77,  85,  88,  144, 
276. 

Cypraeidae,  144. 

Cythere  angusticostata,  121. 

Cythere  desha^^esiana,  120. 

Cythere  edwardsi,  121. 

Cythere  hebertiana,  120. 

Cythere  macropora,  121. 

Cjdhere  marjdandica,  60,  74,  75,  119, 
268. 

Cjdhere  punctata,  120. 

Cythere  thierensiana,  120. 

Cjdhere  triangularis,  119.  ’ 

Cythere  trigonula,  119. 

Cjdherea  lenis,  168. 

Cj'therea  lenticularis,  171. 

Cytherea  liciata,  168. 


PALEOXTOLOGICAL  INDEX 


325 


Cj'therea  ovata,  168. 

Cytherea  pyg’a,  169. 

Cytherea  subimpressa,  170. 

O^’tliereis  bassleri,  63,  71,  75,  120,  268. 
Cytheridae,  119. 

Cytheridea  debilis,  122. 

Cytheridea  intermedia,  122. 

Cytheridea  miilleri,  122. 

Cytherella  compressa,  116. 

Cytherella  londinensis,  118. 

Cytherella  marlboroensis,  63,  74,  75, 
111,  118,  268. 

Cytherella  ovata,  118. 

C^'therella  siibmarginata,  63,  74,  75, 
118,  268. 

Cytherellidae,  117. 

Cytheridea  perarcuata,  74,  75,  121,  268. 

D. 

Decapoda,  116. 

Dentaliidae,  158. 

Dentalina  affinis,  236. 

Dentalina  badenensis,  237. 

Dentalina  communis,  237. 

Dentalina  consobrina  var.  emaciata, 
238. 

Dentalina  inornata,  237. 

Dentalina  legnmen,  237. 

Dentalina  sandbergeri,  238. 

Dentalina  subarcuata,  237. 

Dentalium  minutistriatum,  67,  76,  77, 

158,  281. 

Dentalium  mississippiensis,  59,  76,  77, 

159,  281. 

Dentalium  thalloides,  159. 
Diadematidae,  232. 

Diadematoida,  232. 

Dione  liciata,  168. 

Dione  ovata,  168. 

Dione  pyga,  170. 

Diplodonta  hopkinsensis,  173,  1V^,  288. 
Diplodonta  marlboroensis,  63,  72,  78, 
79,  113,  288. 

Diplodonta  ungulifera,  173. 
Diplodontidae,  173. 

Discorbina  bertheloti,  67,  80,  81,  251, 
316. 

Discorbina  turbo,  63,  80,  81,  251,  316. 
Discosparsa  varians,  63,  78,  79,  205, 
311. 

Doliidae,  141. 

Dosinia  lenticularis,  171. 


Dosiniopsis  lenticularis,  61,  68,  69,  71, 
72,  78,  79,  85,  86,  111,  287. 
Dosiniopsis  meekii,  171. 

E. 

Echinodermata,  232. 

Echinoidea,  232. 

Egeria  rotunda,  173. 

Elasmobranchii,  98. 

Ensuchia,  95. 

.Escharidae,  219. 

Eschara  digitata,  80,  81,  216,  312. 
Escharipora,  218. 

Escharipora  immersa,  219. 

Escharipora  incrassata,  219. 
Escharifora  typica,  222. 

Euclastes  (?)  sp.,  61,  74,  75,  91,  262. 
Eulimidae,  156. 

Eupsammia  conradi,  231,  313. 
Eupsammia  elaborata,  60,  62,  80,  81, 
85,  86,  229,  313. 

Eupsammia  (?)  pileolus,  231. 

F. 

Fascipora  pavonina,  207. 

Eascipora  subramosa,  63,  78,  79,  201, 
311. 

Fasciporidae,  207. 

Eissurellidae,  158. 

Fissuridea  marlboroensis,  63,  72,  76, 
77,  158,  281. 

Flabellum  cuneiforme  var.  pachyphyl- 
lum,  223. 

Flabellum  cuneiforme  var.  wailesi, 
223. 

Flabellum  johnsoni,  223. 

Flabellum  sp.,  80,  81,  222,  313. 
Foraminifera,  233. 

Fulgur  argutus,  142. 

Fulguroficus  argutus,  76,  77,  142,  276. 
Fulguroficus  triserialis,  142,  143. 
Fusoficula-  juvenis,  63,  76,  77,  85,  86, 
143,  276. 

Fusidae,  133. 

Fusus  (Hemifusus  ?)  engonatus,  140. 
Fusus  (?),  134. 

Fusus  (?)  interstriatus,  74,  75,  85,  87, 
88,  135,  273. 

Fusus  (Levifusus)  trabeatus,  139. 
Fusus  (Strepsidura)  perlatus,  136. 
Fusus  (Strepsidura)  siibscalarinus, 
136. 

Fusus  (?)  subtenuis,  63,  74,  75,  85,  86, 
134,  274. 


326 


PALEONTOLOGICAL  INDEX 


Fusus  trabeatus,  138. 

Fusus  trabeatus  (?)  var.,  76,  77,  139. 

G. 

Galeocerdo,  109. 

Galeocerdo  latidens,  66,  74,  75,  109,  266. 
Galeocerdo  minor,  109. 

Gastrochaena  sp.,  60,  76,  77,  161,  282. 
Gastrochaenidae,  161. 

Gastropoda,  74,  75,  76,  77,  123. 

Gibbiila  glandula,  60,  72,  76,  77,  151, 
281. 

Globiilina  g-ibba,  248. 

Globigerina  bulloides,  67,  80,  81,  250, 
315. 

Globigerinidae,  250. 

Glycymeris  elong'ata,  162. 

Glycymeris  idoneus,  67,  70,  72,  73,  78, 
79,  85,  86,  88,  191^  302. 

Gryphaea  eversa,  193. 

Gryphaea  vesicularis,  61,  19S,  302. 
Gryphaea  vomer,  193. 

Gryphaeostrea,  193. 

Grj^phaeostrea  vomer,  59,  72,  193. 
Guttulina  austriaca,  244. 

Guttulina  communis,  244. 

Guttulina  nitida,  244. 

Gymnog’lossa,  155. 

H. 

Hexacoralla,  222. 

Hercoglossa  (Eiiclimatoceras)  ulrichi, 
123. 

Hercoglossa  tuomeyi,  71,  74,  75,  122, 
268,  269,  270. 

Heteropora  (?)  tecta,  63,  80,  81,  210, 
311. 

Heteropora  (Multicrescis)  parvicella, 
209. 

I. 

Idmoniidae,  207. 

Ischyrhiza  (?)  radiata,  112. 

L. 

Lagenidae,  236. 

Lamna,  103,  106. 

Lamna  acuminata,  106. 

Lamna  clavata,  105. 

Lamna  compressa,  105. 

Lamna  compressa  (pars),  110. 

Lamna  cuspidata,  105. 

Lamna  elegans,  104,  105. 


Lamna  (?)  obliqua,  106. 

Lamnidae,  108. 

Latiarca  idonea,  196. 

Latiarca  onochela,  196. 

Latiarca  transversa,  196. 

Latiarca  gigantea,  196. 

Latirus  marylandicus,  63,  74,  75,  133, 
273. 

Leda  (Adrana)  cultelliformis,  198. 
Leda  cliftonensis,  60,  78,  79,  200,  201, 
308. 

Leda  cultelliformis,  67,  70,  78,  79,  198, 
308. 

Leda  improcera,  64,  67,  78,  79,  199,  200, 
308. 

Leda  parilis,  72,  78,  79,  199,  309. 

Leda  parilis  var.,  66,  78,  79,  200,  309. 
Leda  parva,  67,  78,  79,  85,  86,  88,  191, 
308. 

Leda  pharcida,  201. 

Leda  potomacensis,  64,  78,  79,  85,  88, 
200,  308. 

Leda  j)rotexta,  200,  201. 

Leda  tysoni,  64,  78,  79,  201,  309. 
Ledidae,  199. 

Lenticulites  rotulata,  242. 

Leimalia  labiosa,  63,  80,  81,  220,  312. 
Lepralia  subplana,  63,  80,  81,  219,  311. 
Levifusus  trabeatus  (?),  66,  76,  77,  138. 
Levifusus  trabeatus  (?)  var.,  66,  76,  77, 
85,  88,  89,  139,  275. 

Limopsidae,  195. 

Limopsis  decisus,  195. 

Litiopa  marylandica,  76,  77,  152,  280. 
Lithophaga  marylandica,  61,  78,  79, 
186,  295. 

Littorinidae,  152. 

Lucina  aquiana,  60,  72,  78,  79,  85,  86, 
llJf,  289. 

Lucina  astartiformis,  65,  67,  78,  79,  85, 
88,  115,  289. 

Lucina  claibornensis,  177. 

Lucina  dartoni,  64,  67,  78,  79,  115,  289. 
Lucina  greggi,  174. 

Lucina  sp.,  78,  79,  111. 

Lucina  uhleri,  59,  67,  78,  79,  85,  87,  88, 
116,  289. 

Lucina  ulrichi,  176. 

Lucina  whitei,  64,  67,  78,  79,  116,  289. 
Lucinidae,  174. 

Lunatia  eminula,  151. 

Lunatia  marylandica,  59,  76,  77,  85,  86, 
88,  89,  151,  280. 

Lunulites  patelliformis,  217. 


PALEONTOLOGICAL  INDEX 


327 


Lnnulites  regularis,  217. 

Luniilites  reversa,  63,  80,  81,  211,  312. 
Lunulites  semilunaris,  217. 

M. 

Malacostraca,  116. 

Mangilia  (Pleurotomella)  bellistriata 

74,  75,  128,  272. 

Marginulina,  240. 

Marg’inulina  costata,  63,  80,  81,  2'fO, 
315. 

Melong'ena  (?)  potomacensis,  63,  74, 

75,  136,  274. 

Melong-ena  subcarinata,  137. 
Membranipora  angusta,  63,  80,  81,  213, 
312. 

Membranipora  lineata,  213. 
Membranipora  perampla,  212. 
Membranipora  rimulata,  63,  80,  81,  211, 
312. 

Membranipora  spiculosa,  63,  80,  81, 
212,  214,  215,  312. 
^tembraniporidae,  211. 

Meretrix  lenis,  67,  76,  77,  168,  285. 
Meretrix  liceata,  168. 

Meretrix  nuttalliopsis,  169. 

Meretrix  ovata,  168. 

Meretrix  ovata  var.  ovata,  64,  65,  76, 
77,  168,  286. 

Meretrix  ovata  var.  pyga,  60,  61,  68,  69, 
71,  72,  73,  78,  79,  85,  88,  169,  286. 
Meretrix  pyga,  170. 

Meretrix  subimpressa,  67,  70,  71,  78, 
79,  85,  88,  110,  286. 

Mesalia  obruta,  70,  71,  72,  76,  77,  85,  87, 
88,  Ui9,  279. 

Metula  marylandica,  63,  76,  77,  139, 
275. 

Microporidae,  216. 

Mitra  marjdandica,  63,  74,  75,  132,  273. 
Mitra  pomonkensis,  63,  74,  75,  132,  273. 
Mitra  potomacensis,  70,  71,  74,  75,  133, 
273. 

Mitra  sp.,  132. 

Mitsikurina,  1C3. 

Modiola  alabamensis,  185. 

Modiola  potomacensis,  185. 

Modiolus  alabamensis,  59,  78,  79,  85, 
87,  88,  185,  295. 

^Modiolus  marylandicus,  67,  71,  78,  79, 
186,  295. 

Modiolus  (Brachydontes)  potomac- 
ensis, 185. 

Molluscoidea,  78,  79,  80,  81,  203. 


Mollusca,  74,  75,  76,  77,  78,  79,  122. 
Monodonta  glandula,  157. 

Morio  brevidentata,  63,  76,  77,  85,  86, 
lU,  276. 

Mucronella  aspera,  63,  80,  81,  221,  312. 
Multicrescis  parvicella,  259. 

Muricidea,  135. 

Myliobatis,  98. 

Myliobatis  copeanus,  59,  74,  75,  99,  264, 
265. 

Myliobatis  holmesii,  100. 

Mjdiobatis  magister,  100,  264,  265. 
Myliobatis  pacbyodon,  99. 

Myliobatis  pentoni,  100. 

Myliobatis  sp.,  101,  265. 

Myliobatidae,  98. 

Mytilidae,  185. 

N. 

Narona,  129. 

Naticidae,  150. 

Natica  cliftonensis,  76,  77,  150,  280. 
Natica  eminula  var.,  151. 

ISTautiloidea,  122. 

Nautilus  (Ortlioceras)  costatus,  240. 
Nautilus  legumen,  240. 

Nautilus  lobatulus,  252. 

Nautilus  obliquus,  239. 

Nautilus  sp.,  122. 

Niso  umbilicata,  63,  76,  77,  85,  86,  156, 
281. 

Nodosaria  affinis,  66,  80,  81,  236,  314. 
Nodosaria  bacillum,  59,  80,  81,  236,  314. 
Nodosaria  communis,  60,  80,  81,  231, 
314. 

Nodosaria  consorbrina  v.  emaciata, 
63,  80,  81,  238,  314. 

Nodosaria  obliqua,  63,  80,  81,  239,  314. 
Nodosaria  sandbergeri,  63,  80,  81,  238, 
314. 

Nodosaridae,  236. 

Noetia  pulchra,  195. 

Nonionina  affinis,  67,  80,  81,  251,  316. 
Nonionina  punctata,  257. 

Nucula  capsiopsis,  201. 

Nuciila  cultelliformis,  198. 

Nucula  improcera,  199. 

Nucula  magnifica,  2f,2. 

Nucula  ovula,  72,  78,  79,  85,  86,  202, 
309. 

Nucula  parilis,  199. 

Nucula  parva,  197. 

Nucula  potomacensis,  64,  67,  78,  79. 
202,  309. 


328 


PALEONTOLOGICAL  INDEX 


Niiculana  cultelliformis,  198. 

Nuciilana  improcera,  199. 

Nuciilana  parva,  197. 

Nuculana  protexta,  200,  201. 

Niiculidae,  202. 

O. 

Odontaspis,  103,  106. 

Odontaspis  cuspidata,  59,  71,  75,  105, 
266. 

Odontaspis  eleg-ans,  61,  74,  75,  105,  266. 
Odontaspis  hopei,  105. 

Odontaspis  macrota,  61,  74,  75,  104, 
105,  266. 

Odostomia  insig’nifica,  156. 

Odostomia  trapaqiiara,  63,  76,  77,  85, 
86,  87,  156,  281. 

Olividae,  130. 

Olivnla  sp.,  66,  74,  75,  130. 

Olivula  staminea,  130. 

Onychocella,  216. 

Opisthobranchiata,  123. 
Orthochaenites,  122. 

Oryctomya,  183. 

Osteodes  elaborata,  229. 

Ostrea  bellovacina,  190. 

Ostrea  compressirostra,  60,  61,  64,  66, 
69,  71,  72,  73,  78,  79,  85,  86,  190,  191, 

192,  297,  298. 

Ostrea  compressirostra  var.  alepido- 
ta,  61,  62,  78,  79,  191. 

Ostrea  (Gryphaeostrea)  subeversa, 

193. 

Ostrea  (Gryphaeostrea)  vomer,  59,  78, 
79,  85,  87,  89,  193,  302. 

Ostrea  sellaeformis,  64,  67,  70,  78,  79, 
83,  85,  88,  89,  191,  192,  300,  301. 
Ostrea  sinuosa,  190. 

Ostrea  sp.,  193. 

Ostrea  subeversa,  193. 

Ostracoda,  74,  75,  116. 

Ostreidae,  190. 

Otodns  macrotus,  105. 

Otodns  obliquus,  61,  74,  75,  106,  267. 
Otolites,  113,  264. 

Oxyrhina,  106. 

P. 

Panopea  elongata,  60,  69,  72,  73,  76,  77, 
162,  282. 

Papillina  staminea  var.,  137. 
Paracyathus  alternatns,  227. 
Parac3mthus  (?)  clarkeanus,  225. 


Paraej'athus  granulosus,  227. 
Parac^'athus  marylandicus,  63,  80,  81, 
226,  313. 

Parallelodontidae,  196. 

Pasithea  umbilicata,  156. 

Pavolunulites  elegans,  217. 

Pecten  calvatus,  189. 

Pecten  clioctavensis,  59,’  78,  79,  85,  87, 
88,  188,  189,  296. 

Pecten  dalli,  67,  70,  78,  79,  85,  87,  89, 
188,  296. 

Pecten  (Pseudamusium)  frontalis,  188. 
Pecten  greggi,  189. 

Pecten  johnsoni,  78,  79,  85,  86,  88,  189, 
190,  296. 

Pecten  rogersi,  188. 

Pecten  sp.,  63,  78,  79,  190,  296. 

Pecten  w^ahtubbeanus,  190. 

Pectinidae,  188. 

Pectunculus  decisus,  195. 

Pectunculus  idoneus,  194. 

Pelecypoda,  76,  77,  78,  79,  160. 
Periploma  (?)  sp.,  65,  78,  79,  185. 
Periidomidae,  184. 

Peronidia,  167. 

Plienaeom^'a  petrosa,  62,  76,  77,  161, 
282. 

Plioladom\'a  marjdandica,  62,  69,  78, 
79,  185,  295. 

Pholadomyidae,  184. 

Pholas  petrosa,  161. 

Pholadidae,  161. 

Phyllodus,  112. 

Phyllodus  hipparionj'x,  113. 

Ph\dlodus  sp.  aff.  toliapicus,  113. 
Phyllodus  toliapicus,  112. 
Ph\"matocor3"on  mackajd,  259. 

Pisces,  74,  75,  93,  98. 

Placosmilia  (Trochosmilia)  connivens, 
229,  230. 

Plantae,  80,  81,  93,  258,  316. 

Platidia  marjdaudica,  63,  72,  78,  79, 
203,  310. 

Pleurophoridae,  183. 

Pleurotoma  childreni,  63,  74,  75,  85, 
86,  121,  272. 

Pleurotoma  ducateli,  63,  74,  75,  126, 
272. 

Pleurotoma  denticula,  127. 

Pleurotoma  denticula  var.,  127. 
Pleurotoma  harrisi,  63,  74,  75,  125,  126, 
272. 

Pleurotoma  (Hemipleurotoma)  chil- 
dreni, 127. 


PALEONTOLOGICAL  INDEX 


329 


Pleurotoma  nasuta,  126. 

Pleurotoma  piscatavensis,  63,  74,  75, 
121,  272. 

Pleurotoma  potomacensis,  63,  74,  75, 
126,  272. 

Pleurotoma  tysoni,  63,  74,  75,  126,  272. 
Pleurotomella  bellistriata,  128. 
Pleurotomiclae,  125. 

Polymorpliina  anceps,  247. 
Polymorphina  austriaca,  66,  80,  81, 

2U,  315. 

Polymorpliina  communis,  80,  81,  21flf, 

248,  315. 

Polymorphina  complanata,  246. 
Polymorphina  compressa,  80,  81,  2.'i6, 
315. 

Polymorphina  cylinclroides,  246. 
Polymorphina  eleffantissima,  66,  80, 
81,  247,  315. 

PolymoriDhina  froncliformis,  246. 
Polymorphina  g-ibba,  59,  80,  81,  21^8, 

249,  315. 

Polymorphina  lactea,  63,  80,  81,  2.’iS, 

315. 

Polymorphina  praelonga,  66,  80,  81, 
^2If9,  315. 

Polymorphina  problema,  244,  245,  249. 
Polymorphina  problema  var.  deltoi- 
dea,  247. 

Prionodesmacea,  185. 

Protocardia  lenis,  59,  67,  70,  71,  73,  78, 
79,  112,  288. 

Protocardia  virginiana,  172. 
Protosphj^raena,  111. 

Protozoa,  80,  81,  233. 

Pseudoliva  sp.,  63,  76,  77,  UO,  264. 
Pseudoliva  venusta,  140. 

Pteria  limula,  72,  78,  79,  85,  87,  88,  89, 
lO.’f,  303. 

Pteriidae,  194. 

Ptenoglossa,  153. 

Pulvinulina  exigua  var.  obtusa,  80,  81, 
255,  316. 

Pulvinulina  karsteni,  256. 

Pulvinulina  schreibersii,  67,  80,  81,  256, 

316. 

Pyramidellidae,  155. 

Pyrgiscus,  155. 

Pyropsis  pyrula,  137,  138. 

Pyropsis  (?)  sp.,  138. 

Pyrula  cancellata,  141. 

Pyrula  elegantissima,  141,  142. 

Pyrula  juvenis,  143. 


Pyrula  penita  var.,  66,  76,  77,  85,  88,  89, 
Ul,  276. 

Pyrula  (?)  sp.,  66,  76,  77,  lJi.2,  276. 
Pyrula  tricarinata,  141. 

R. 

Eachiglossa,  130. 

Ileptescharipora,  218. 

Eeptilia,  74,  75,  95. 

Eeptocelleporaria  aspera,  220. 
Eeptofiustrella  heteropora,  80,  81,  213. 
312. 

Eeticulipora  dichotoma,  63,  78,  79,  201, 
311. 

Ehipidoglossa,  157. 

Ehizopoda,  233. 

Eingicula  dalli,  67,  70,  74,  12J^,  272. 
Eingiculidae,  124. 

Eobulina  concinna,  241. 

Eobulina  radiata,  243. 

Eosalina  ammonoides,  254. 

Eosalina  bertheloti,  251. 

Eotalia  (Trochulina)  turbo,  251. 
Eotalidae,  251. 

Eotalina  schreibersii,  256. 

Eotalina  ungeriana,  253. 

S. 

Saxicavidae,  162. 

Scala  carinata,  63,  76,  77,  154,  280. 
Scala  potomacensis,  63,  76,  77,  154,  280. 
Scala  sessilis,  63,  76,  77,  154,  280. 

Scala  virginiana,  60,  76,  77,  153,  280. 
Scalariidae,  153. 

Scapanorhynchus,  103. 

Scaphandridae,  124. 

Scaphopoda,  76,  77,  158. 

Selachian  vertebrae,  110. 
SemiescharijDora,  218. 

Serpula  lactea,  248. 

Simpulum  showalteri,  141. 
Siphonodentaliidae,  159. 

Solariidae,  153. 

Solarium  sp.,  60,  76,  77,  153,  280. 

Solen  lisbonensis  (?),  65,  76,  77,  165, 
285. 

Solen  (Plectosolen)  lisbonensis,  165. 
Solen  (Plectosolen)  lisbonensis  var. 

abrnptus,  165. 

Solen  sp.,  165. 

Solenidae,  165. 

Solenoconchia,  158. 

Solemya  petricoloides,  186. 
Spatangidae,  232. 


330 


PALEONTOLOGICAL  INDEX 


Spatang-idea,  232. 

Sphyraena  speciosa,  111. 

Sphyrna,  109. 

Spliyrna  denticulata,  110. 

Sphyrna  i^risca,  61,  74,  75,  110,  266. 
Spiroihecta  americana,  235. 

Spiroplecta  biformis,  236. 

Spirof)lecta  clarki,  66,  80,  81,  235,  314. 
Sqnalus  aiiricnlatus,  108. 

Strepsidura  subscalarina,  59,  70,  74, 
75,  136,  274. 

Strombidae,  145. 

Synechodns,  102. 

Synechodus  clarkii,  61,  74,  75,  103,  266. 
Syrnola  trapaqiiara,  156. 

T. 

Taenioglossa,  141. 

Tectibranchiata,  123. 

Tectospondyli,  98. 

Teleodesmacea,  160. 

Teleostomi,  110,  264. 

Teleotremata,  203. 

Tellina  greg-gi,  166. 

Tellina  siibtriangularis,  167. 

Tellina  virginiana,  59,  76,  77,  166,  285. 
Tellina  williamsi,  76,  77,  167,  285. 
Tellina  (Angelus)  virginiana,  166. 
Tellina  (Peronidae)  iDapyria  (?),  76, 
77,  167 

Tellina  (Peronidia  ?)  williamsi,  167. 
Tellinidae,  166. 

Terebratellidae,  203. 

Terebratula  harlani,  61,  78,  79,  194,  20J^, 
310. 

Terebratnlidae,  204. 

Teredinidae,  160. 

Teredo  virginiana,  76,  77,  160,  282. 
Testndenata,  97. 

Tetrabranchiata,  122. 

Textularia  abbreviata,  233. 

Textnlaria  hauerii,  233. 

Textularia  gramen,  63,  80,  81,  233,  314. 
Textularia  sagittula,  63,  80,  81,  231f, 
314. 

Textularia  subangulata,  61,  80,  81,  231f, 
314. 

Textularidae,  233. 

Thecaehampsa  antiqua,  96. 
Thecaehampsa  eontusor,  61,  74,  75,  96, 
262. 

Thecaehampsa  marylandica,  60,  74,  75, 
96,  262. 


Thecaehampsa  sericodon  (?),  61,  74, 
75,  95,  262. 

Thecaehampsa  sp.,  60,  74,  75,  95,  262. 
Tornatella  bella,  123. 

Tornatellaea  bella,  59,  66,  70,  74,  75,  85, 
86,  88,  123,  272. 

Toxoglossa,  125. 

Trigonoarca  decisa  var.,  78,  79,  85,  88, 
195,  303. 

Trigonoarca  pulchra,  195. 

Trigonoarca  pulchra  var.,  195. 
Trionychia,  97. 

Trionychidae,  97. 

Trionyx  virginiana,  61,  74,  75,  97,  263. 
Tritonidae,  141. 

Tritonium  showalteri,  63,  76,  77,  llfl, 
276. 

Trochidae,  157. 

Trochocyathus  clarkeanus,  60,  62,  80, 
81,  225,  313. 

Trochosmilia  connivens,  229. 

Trochus  apertus,  152. 

Trophon  sublevis,  63,  74,  75,  85,  86,  135, 

274. 

Truncatulina  boueana,  253. 
Truncatulina  grosserugosa,  254. 
Truncatulina  lobatula,  80,  81,  251,  252, 
316. 

Truncatulina  refulgens,  252. 
Truncatulina  ungeriana,  59,  80,  81, 

253,  316. 

Truncatulina  variabilis,  253. 
Truncatulina  wuellerstorfi,  253. 

Tuba  marylandica,  76,  77,  155,  281. 
Tubuliporidae,  205. 

Tudicla  marylandica,  63,  76,  77,  137, 

275. 

Tudicla  sp.,  61,  62,  76,  77,  138,  275. 
Tudicla  (?)  sp.,  76,  77,  138,  275,  276. 
Turbinella  pyruloides,  131. 

Turbinolia  acuticostata,  43,  62,  80,  81, 
223,  313. 

Turbinolia  elaborata,  229. 

Turbinolia  pharetra,  224,  225. 
Turbinolia  pileolus,  231. 

Turbinolia  wautubbeensis,  224. 
Turbinolidae,  222,  223. 

Turbonilla  potomacensis,  63,  76,  77, 
155,  281. 

Turritella  humerosa,  60,  61,  64,  69,  71, 
72,  76,  77,  85,  86,  UfS,  279. 

Turritella  mortoni,  60,  61,  62,  64,  68,  69, 
72,  73,  76,  77,  85,  86,  U7,  148,  149, 
278. 


TALEOXTOLOGICAL  INDEX 


331 


Turritella  mortoni  var.  postmortoni, 
147. 

Turritella  obruta,  149. 

Turritella  potomacensis,  67,  70,  71,  76, 
77,  U9,  279. 

Turritella  venusta,  149. 

Turritellidae,  147. 

V. 

Vaginulina  leg'umen,  61,  80,  81,  210, 
315. 

Venericardia,  177. 

Venericardia  ascia,  177. 

Venericardia  marjdandica,  67,  78,  79, 
m,  292. 

Venericardia  pectuncularis,  179. 

Venericardia  planicosta,  177,  178. 

Venericardia  planicosta  var.  regia,  60, 
72,  73,  78,  79,  85,  778,  290,  291,  292. 


Venericardia  potapacoensis,  64,  65,  66, 
69,  70,  71,  72,  78,  79,  119,  292. 
Venericardia  regia,  178. 

Veneridae,  168. 

Vermetidae,  150. 

Vermetus  sp.,  60,  76,  77,  150,  279. 
Vertebrata,  95. 

Voluta  petrosa,  130. 

Volutidae,  130. 

Volutilitlies  (Athleta)  tuomeyi,  130. 
Volutilithes  petrosus,  59,  74,  75,  85,  86, 
88,  130,  273. 

Volutilithes  sp.,  60,  74,  75,  131,  273. 

X. 

Xiphias,  111. 

Xiphias  (?)  radiata,  61,  74,  75,  112,  264. 

Y. 

Yoldia  cultelliformis,  198. 


ERRATA. 


PAGE 

61  line  10  for 

63  “ 14  “ 

63  “36  “ 

63  “ 43  “ 

80  “ 35  “ 

81  “ 35  “ 

82  “ 14  “ 

Plate  XX  “ 


Odotus  ohliquus  read  Otodas  ohliquus. 

Reticulipora  dichomata  read  ReticuUpora  dichotoma. 
2Iarginula  costata  read  Marginulina  costata 
Fissuridea  marylandica  read  Fissuridea  marlhoroensis 
Marginula  costata  read  Margin  ulina  costata 


therefore  read  their 
Cephalopoda  read  Gastropoda. 


